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<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title>蒟蒻sxy的blog</title>
<link href="/atom.xml" rel="self"/>
<link href="http://www.sxyoi.cn/"/>
<updated>2020-02-24T07:47:09.732Z</updated>
<id>http://www.sxyoi.cn/</id>
<author>
<name>sxy</name>
</author>
<generator uri="http://hexo.io/">Hexo</generator>
<entry>
<title>Java入门反思</title>
<link href="http://www.sxyoi.cn/2020/02/23/%E6%96%B0%E7%94%9F/"/>
<id>http://www.sxyoi.cn/2020/02/23/新生/</id>
<published>2020-02-23T05:13:18.000Z</published>
<updated>2020-02-24T07:47:09.732Z</updated>
<content type="html"><![CDATA[<p>这几天被疫情困在家里</p><p>于是乎看了一下Java</p><p>感觉Java最不同于我之前学OI的时候的学的编程的地方就是面向对象的这种方式</p><p>也需要花更多的时间来想怎么能提高代码的可维护性，比如避免多个类用到的变量冲突、文件目录等等</p><p>但纸上得来终觉浅，还是要多实际操作一下，不然总是会觉得某些实际上挺有用的东西十分冗余，同时多看一些优秀的开源项目，学习他们优秀的地方</p>]]></content>
<summary type="html">
<p>这几天被疫情困在家里</p>
<p>于是乎看了一下Java</p>
<p>感觉Java最不同于我之前学OI的时候的学的编程的地方就是面向对象的这种方式</p>
<p>也需要花更多的时间来想怎么能提高代码的可维护性，比如避免多个类用到的变量冲突、文件目录等等</p>
<p>但
</summary>
<category term="Java" scheme="http://www.sxyoi.cn/tags/Java/"/>
</entry>
<entry>
<title>【JLOI2011】飞行路线</title>
<link href="http://www.sxyoi.cn/2018/11/08/%5BJLOI2011%5D%E9%A3%9E%E8%A1%8C%E8%B7%AF%E7%BA%BF/"/>
<id>http://www.sxyoi.cn/2018/11/08/[JLOI2011]飞行路线/</id>
<published>2018-11-08T15:52:00.000Z</published>
<updated>2018-11-08T15:58:06.698Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P4568" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>dp+dijkstra（大概吧，但是感觉就只是堆优化spfa，但是都说这也是dijkstra，而且想了一下这样好像还能处理负权图，但是不知道时间复杂度是不是能优化？）</p><p>dis[i]/[j]表示到i点用了j次免费机票的最短距离</p><p>然后堆的元素是这样的</p><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Node</span>{</span></span><br><span class="line"> <span class="keyword">int</span> num,k;</span><br><span class="line"> <span class="keyword">bool</span> <span class="keyword">operator</span><(<span class="keyword">const</span> Node&b)<span class="keyword">const</span></span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">return</span> dis[num][k]>dis[b.num][b.k];</span><br><span class="line"> }</span><br><span class="line">};</span><br></pre></td></tr></table></figure><p>num是点的序号,k是用了多少次免费机票</p><p>其实好像可以拆成多个点。。。一样的。。。反正最后跑下来挺快的。。。其实还是一道比较简单的省选题。。。luogu评分真的是不敢恭维啊。。。</p><p>大概是最后一次这样写题解了吧，oi生涯还真是短暂啊</p><p>回忆录就等考完再写吧（虽然我这么菜也没什么好回忆的</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 10010</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXM 100010</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v;</span><br><span class="line">}e[MAXM];</span><br><span class="line"><span class="keyword">int</span> last[MAXN],dis[MAXN][<span class="number">11</span>],cnt,n,m,k,s,t;</span><br><span class="line"><span class="keyword">bool</span> inq[MAXN][<span class="number">11</span>];</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Node</span>{</span></span><br><span class="line"> <span class="keyword">int</span> num,k;</span><br><span class="line"> <span class="keyword">bool</span> <span class="keyword">operator</span><(<span class="keyword">const</span> Node&b)<span class="keyword">const</span></span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">return</span> dis[num][k]>dis[b.num][b.k];</span><br><span class="line"> }</span><br><span class="line">}; </span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">dijkstra</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> Node u;</span><br><span class="line"> <span class="keyword">long</span> <span class="keyword">long</span> ans=<span class="number">-1</span>;</span><br><span class="line"> <span class="keyword">int</span> tk,temp;</span><br><span class="line"> <span class="keyword">bool</span> tag;</span><br><span class="line"> priority_queue<Node> q;</span><br><span class="line"> rep(i,<span class="number">0</span>,n)</span><br><span class="line"> rep(j,<span class="number">0</span>,k)</span><br><span class="line"> dis[i][j]=<span class="number">-1</span>;</span><br><span class="line"> dis[s][<span class="number">0</span>]=<span class="number">0</span>;</span><br><span class="line"> q.push((Node){s,<span class="number">0</span>});</span><br><span class="line"> inq[s][<span class="number">0</span>]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> u=q.top();q.pop();</span><br><span class="line"> temp=last[u.num];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[u.num][u.k]+e[temp].v<dis[e[temp].to][u.k]||dis[e[temp].to][u.k]<<span class="number">0</span>)</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to][u.k]=dis[u.num][u.k]+e[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to][u.k])</span><br><span class="line"> {</span><br><span class="line"> q.push((Node){e[temp].to,u.k});</span><br><span class="line"> inq[e[temp].to][u.k]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(u.k+<span class="number">1</span><=k&&(dis[u.num][u.k]<dis[e[temp].to][u.k+<span class="number">1</span>]||dis[e[temp].to][u.k+<span class="number">1</span>]<<span class="number">0</span>))</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to][u.k+<span class="number">1</span>]=dis[u.num][u.k];</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to][u.k+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> q.push((Node){e[temp].to,u.k+<span class="number">1</span>});</span><br><span class="line"> inq[e[temp].to][u.k+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> inq[u.num][u.k]=<span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">0</span>,k)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[t][i]<<span class="number">0</span>)</span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> <span class="keyword">if</span>(dis[t][i]<ans||ans<<span class="number">0</span>)</span><br><span class="line"> ans=dis[t][i];</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz;</span><br><span class="line"> n=read();m=read();k=read();</span><br><span class="line"> s=read();t=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz);add(ty,tx,tz);</span><br><span class="line"> }</span><br><span class="line"> dijkstra();</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P4568" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="动态规划" scheme="http://www.sxyoi.cn/tags/%E5%8A%A8%E6%80%81%E8%A7%84%E5%88%92/"/>
<category term="最短路" scheme="http://www.sxyoi.cn/tags/%E6%9C%80%E7%9F%AD%E8%B7%AF/"/>
</entry>
<entry>
<title>纪念品分组</title>
<link href="http://www.sxyoi.cn/2018/11/08/%E7%BA%AA%E5%BF%B5%E5%93%81%E5%88%86%E7%BB%84/"/>
<id>http://www.sxyoi.cn/2018/11/08/纪念品分组/</id>
<published>2018-11-08T15:51:00.000Z</published>
<updated>2018-11-08T15:52:52.345Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1094" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>尽量把大的和小的放一起，先放大的后放小的，两个指针向中间移动</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><stack></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="keyword">int</span> w,n,p[<span class="number">30010</span>];</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> l,r,temp,ans=<span class="number">0</span>;</span><br><span class="line"> <span class="built_in">scanf</span>(<span class="string">"%d%d"</span>,&w,&n);</span><br><span class="line"> l=<span class="number">1</span>,r=n;</span><br><span class="line"> rep(i,<span class="number">1</span>,n)<span class="built_in">scanf</span>(<span class="string">"%d"</span>,&p[i]);</span><br><span class="line"> sort(p+<span class="number">1</span>,p+n+<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(l<=r)</span><br><span class="line"> {</span><br><span class="line"> ++ans;</span><br><span class="line"> temp=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>(r>=l&&temp+p[r]<=w)</span><br><span class="line"> temp+=p[r--];</span><br><span class="line"> <span class="keyword">while</span>(l<=r&&temp+p[l]<=w)</span><br><span class="line"> temp+=p[l++];</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">cout</span><<ans;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1094" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="贪心" scheme="http://www.sxyoi.cn/tags/%E8%B4%AA%E5%BF%83/"/>
</entry>
<entry>
<title>转圈游戏</title>
<link href="http://www.sxyoi.cn/2018/11/08/%E8%BD%AC%E5%9C%88%E6%B8%B8%E6%88%8F/"/>
<id>http://www.sxyoi.cn/2018/11/08/转圈游戏/</id>
<published>2018-11-08T15:48:00.000Z</published>
<updated>2018-11-08T15:50:28.073Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1965" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>直接快速幂+取模。。。没什么好说的</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><stack></span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="keyword">int</span> n,m,k,x;</span><br><span class="line"><span class="function"><span class="keyword">long</span> <span class="keyword">long</span> <span class="title">f_pow</span><span class="params">(<span class="keyword">long</span> <span class="keyword">long</span> x,<span class="keyword">long</span> <span class="keyword">long</span> k)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">long</span> <span class="keyword">long</span> ans=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">while</span>(k)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(k&<span class="number">1</span>)</span><br><span class="line"> {</span><br><span class="line"> ans*=x;</span><br><span class="line"> ans%=n;</span><br><span class="line"> }</span><br><span class="line"> x*=x;</span><br><span class="line"> x%=n;</span><br><span class="line"> k>>=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="built_in">scanf</span>(<span class="string">"%d%d%d%d"</span>,&n,&m,&k,&x);</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%lld"</span>,(x+<span class="number">1L</span>L*f_pow(<span class="number">10</span>,k)*m)%n);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1965" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="快速幂" scheme="http://www.sxyoi.cn/tags/%E5%BF%AB%E9%80%9F%E5%B9%82/"/>
</entry>
<entry>
<title>【USACO08JAN】电话线Telephone Lines</title>
<link href="http://www.sxyoi.cn/2018/11/08/%5BUSACO08JAN%5D%E7%94%B5%E8%AF%9D%E7%BA%BFTelephone%20Lines/"/>
<id>http://www.sxyoi.cn/2018/11/08/[USACO08JAN]电话线Telephone Lines/</id>
<published>2018-11-08T15:38:00.000Z</published>
<updated>2018-11-08T15:47:30.324Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1948" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>一开始看错题了。。。消费为路径上的最大值。。。所以没有想二分答案。。。</p><h3>1.</h3><p>免费连k条相当于把k条权值变成0</p><p>显然每个点的dis可以这样记录：</p><p>dis[i]/[j]表示到点i消掉了j条边</p><p>然后跑最短路，dis按题目要求来就好了</p><p>应该是动态规划吧。。。</p><p>其实我这个松弛还可以优化一下，具体可以看飞行路线那题，每个点没必要每次把所有的0~k都松弛一遍，只需要松弛被松弛的就行了</p><h3>2.</h3><p>二分答案+spfa</p><p>因为消耗是路径上的边权最大值，所以是可以二分答案的</p><p>judge的时候转换一下，把所有边权大于maxx的边权值设为1，不大于maxx的边权值设为0</p><p>然后跑一边spfa，看dis[n]是不是小于等于k即可</p><p>一开始的左边界设错了。。。二分的左边界应该一直是0，我设置为了最小边权，然后就在bzoj上一直wa，但是luogu上可a。。。数据水？</p><h2>Code</h2><h2>Code</h2><h3>1.</h3><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v;</span><br><span class="line">}e[<span class="number">20001</span>];</span><br><span class="line"><span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"><span class="keyword">long</span> <span class="keyword">long</span> dis[<span class="number">1001</span>][<span class="number">10001</span>],ans=<span class="number">-1</span>;</span><br><span class="line"><span class="keyword">int</span> last[<span class="number">1001</span>],n,p,k,cnt;</span><br><span class="line"><span class="keyword">bool</span> inq[<span class="number">1001</span>];</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="title">max</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &a,<span class="keyword">const</span> <span class="keyword">int</span> &b)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> a>b?a:b;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz,temp,u;</span><br><span class="line"> <span class="keyword">bool</span> tag;</span><br><span class="line"> n=read();p=read();k=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,p)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz);</span><br><span class="line"> add(ty,tx,tz);</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> rep(j,<span class="number">0</span>,k)</span><br><span class="line"> dis[i][j]=<span class="number">-1</span>;</span><br><span class="line"> dis[<span class="number">1</span>][<span class="number">0</span>]=<span class="number">0</span>;</span><br><span class="line"> inq[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())<span class="comment">//这里可以优化，但是空间消耗会大一点，具体可见飞行路线</span></span><br><span class="line"> {</span><br><span class="line"> u=q.front();q.pop();</span><br><span class="line"> rep(i,<span class="number">0</span>,k)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[u][i]<<span class="number">0</span>)</span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> temp=last[u];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> tag=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">if</span>(dis[e[temp].to][i]<<span class="number">0</span>||max(dis[u][i],e[temp].v)<dis[e[temp].to][i])</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to][i]=max(dis[u][i],e[temp].v);</span><br><span class="line"> tag=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(i+<span class="number">1</span><=k&&(dis[e[temp].to][i+<span class="number">1</span>]<<span class="number">0</span>||dis[u][i]<dis[e[temp].to][i+<span class="number">1</span>]))</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to][i+<span class="number">1</span>]=dis[u][i];</span><br><span class="line"> tag=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(tag&&!inq[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> inq[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> inq[u]=<span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">0</span>,k)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[n][i]<<span class="number">0</span>)</span><br><span class="line"> <span class="keyword">continue</span>;</span><br><span class="line"> <span class="keyword">if</span>(ans<<span class="number">0</span>)</span><br><span class="line"> ans=dis[n][i];</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> ans=min(ans,dis[n][i]);</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%lld"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure><h3>2.</h3><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v,v_sb;</span><br><span class="line">}e[<span class="number">20001</span>];</span><br><span class="line"><span class="keyword">int</span> n,p,k,last[<span class="number">1001</span>],cnt,dis[<span class="number">1001</span>];</span><br><span class="line"><span class="keyword">bool</span> inq[<span class="number">1001</span>];</span><br><span class="line"><span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v_sb=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">bool</span> <span class="title">judge</span><span class="params">(<span class="keyword">int</span> maxx)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp,u;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> dis[i]=<span class="number">-1</span>;</span><br><span class="line"> rep(i,<span class="number">1</span>,cnt)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(e[i].v_sb>maxx)</span><br><span class="line"> e[i].v=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> e[i].v=<span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> dis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> inq[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> u=q.front();q.pop();</span><br><span class="line"> <span class="comment">/*if(dis[u]>k)</span></span><br><span class="line"><span class="comment"> {</span></span><br><span class="line"><span class="comment"> inq[u]=0;</span></span><br><span class="line"><span class="comment"> continue;</span></span><br><span class="line"><span class="comment"> }*/</span><span class="comment">//sb的负优化，耗时还多了4ms</span></span><br><span class="line"> temp=last[u];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[e[temp].to]<<span class="number">0</span>||dis[u]+e[temp].v<dis[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to]=dis[u]+e[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> inq[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> inq[u]=<span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(dis[n]>=<span class="number">0</span>&&dis[n]<=k)</span><br><span class="line"> <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz,l=<span class="number">0</span>,r=<span class="number">1</span>,mid,ans;</span><br><span class="line"> n=read();p=read();k=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,p)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> r=max(r,tz);</span><br><span class="line"> add(tx,ty,tz);</span><br><span class="line"> add(ty,tx,tz);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(!judge(r))</span><br><span class="line"> {</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"-1"</span>);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(l<=r)</span><br><span class="line"> {</span><br><span class="line"> mid=l+((r-l)>><span class="number">1</span>);</span><br><span class="line"> <span class="keyword">if</span>(judge(mid))</span><br><span class="line"> {</span><br><span class="line"> ans=mid;</span><br><span class="line"> r=mid<span class="number">-1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> l=mid+<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1948" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="动态规划" scheme="http://www.sxyoi.cn/tags/%E5%8A%A8%E6%80%81%E8%A7%84%E5%88%92/"/>
<category term="二分答案" scheme="http://www.sxyoi.cn/tags/%E4%BA%8C%E5%88%86%E7%AD%94%E6%A1%88/"/>
<category term="最短路" scheme="http://www.sxyoi.cn/tags/%E6%9C%80%E7%9F%AD%E8%B7%AF/"/>
</entry>
<entry>
<title>银河英雄传说</title>
<link href="http://www.sxyoi.cn/2018/11/08/%E9%93%B6%E6%B2%B3%E8%8B%B1%E9%9B%84%E4%BC%A0%E8%AF%B4/"/>
<id>http://www.sxyoi.cn/2018/11/08/银河英雄传说/</id>
<published>2018-11-08T15:35:00.000Z</published>
<updated>2018-11-08T15:38:11.326Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1196" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>跟叠积木差不多，就是询问的时候输出两个权值相减而已</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 30010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a;</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> a[MAXN],b[MAXN],v[MAXN];<span class="comment">//top , bottom , value</span></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">finda</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">if</span>(!a[x])</span><br><span class="line"> <span class="keyword">return</span> x;</span><br><span class="line"> finda(a[x]);</span><br><span class="line"> v[x]+=v[a[x]];</span><br><span class="line"> <span class="keyword">return</span> a[x]=finda(a[x]);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">findb</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> b[x]?b[x]=findb(b[x]):x;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">int</span> tx,ty;</span><br><span class="line"> <span class="keyword">int</span> T=read();</span><br><span class="line"> <span class="keyword">while</span>(T--)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'M'</span>)<span class="comment">//merge</span></span><br><span class="line"> {</span><br><span class="line"> tx=finda(tx);ty=findb(ty);</span><br><span class="line"> v[tx]=<span class="number">1</span>;</span><br><span class="line"> a[tx]=ty;</span><br><span class="line"> b[ty]=findb(tx);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'C'</span>)<span class="comment">//query</span></span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(finda(tx)!=finda(ty))</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"-1\n"</span>);</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d\n"</span>,<span class="built_in">abs</span>(v[tx]-v[ty])<span class="number">-1</span>);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1196" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="并查集" scheme="http://www.sxyoi.cn/tags/%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
<category term="带权并查集" scheme="http://www.sxyoi.cn/tags/%E5%B8%A6%E6%9D%83%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
</entry>
<entry>
<title>路径统计</title>
<link href="http://www.sxyoi.cn/2018/11/07/%E8%B7%AF%E5%BE%84%E7%BB%9F%E8%AE%A1/"/>
<id>http://www.sxyoi.cn/2018/11/07/路径统计/</id>
<published>2018-11-06T16:40:00.000Z</published>
<updated>2018-11-06T16:46:24.228Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1608" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>有点类似最短路计数那道题。。。</p><p>主要问题有两个：去重边，统计最短路条数</p><p>前一个比较好搞，后一个在spfa的时候改一下松弛操作就行了</p><p>但是要在每一个元素出队时将其计数器清零，否则会被以下数据×掉</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">5 5</span><br><span class="line">1 2 1</span><br><span class="line">2 3 1</span><br><span class="line">3 4 1</span><br><span class="line">4 5 1</span><br><span class="line">1 4 3</span><br></pre></td></tr></table></figure><p>因为这组数据如果不清零4会入队两次， 第一次是1->4 (v=3,dis=3,path=1)</p><p>然后4->5 (v=1,dis=4,path=1)</p><p>第二次是3->4(v=1,dis=3,path=1+1)</p><p>然后4->5(v=1,dis=4,path=1+2)</p><p>然后就会输出</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">4 3</span><br></pre></td></tr></table></figure><p>实际是</p><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">4 2</span><br></pre></td></tr></table></figure><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v;</span><br><span class="line">}e[<span class="number">4000001</span>];</span><br><span class="line"><span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="keyword">int</span> last[<span class="number">2001</span>],cnt,dis[<span class="number">2001</span>],ee[<span class="number">2001</span>][<span class="number">2001</span>],cnt_path[<span class="number">2001</span>];</span><br><span class="line"><span class="keyword">bool</span> inq[<span class="number">2001</span>];</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v,<span class="keyword">int</span> &num)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">if</span>(!ee[from][to])</span><br><span class="line"> {</span><br><span class="line"> ee[from][to]=v;</span><br><span class="line"> e[num].next=last[from];</span><br><span class="line"> last[from]=num;</span><br><span class="line"> e[num].to=to;</span><br><span class="line"> e[num].v=v;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(v<ee[from][to])</span><br><span class="line"> {</span><br><span class="line"> ee[from][to]=v;</span><br><span class="line"> e[num].next=last[from];</span><br><span class="line"> last[from]=num;</span><br><span class="line"> e[num].to=to;</span><br><span class="line"> e[num].v=v;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> {</span><br><span class="line"> --num;</span><br><span class="line"> --m;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz,temp;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)dis[i]=<span class="number">-1</span>;</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz,i);</span><br><span class="line"> }</span><br><span class="line"> cnt_path[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> inq[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> temp=last[q.front()];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[e[temp].to]<<span class="number">0</span>||dis[q.front()]+e[temp].v<dis[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to]=dis[q.front()]+e[temp].v;</span><br><span class="line"> cnt_path[e[temp].to]=cnt_path[q.front()];</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> inq[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(dis[q.front()]+e[temp].v==dis[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> cnt_path[e[temp].to]+=cnt_path[q.front()];</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> inq[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(q.front()!=n)</span><br><span class="line"> cnt_path[q.front()]=<span class="number">0</span>;</span><br><span class="line"> inq[q.front()]=<span class="number">0</span>;</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(dis[n]<=<span class="number">0</span>)</span><br><span class="line"> {</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"No answer"</span>);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d %d"</span>,dis[n],cnt_path[n]);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1608" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="最短路" scheme="http://www.sxyoi.cn/tags/%E6%9C%80%E7%9F%AD%E8%B7%AF/"/>
</entry>
<entry>
<title>TJOI2007路标设置</title>
<link href="http://www.sxyoi.cn/2018/11/07/TJOI2007%E8%B7%AF%E6%A0%87%E8%AE%BE%E7%BD%AE/"/>
<id>http://www.sxyoi.cn/2018/11/07/TJOI2007路标设置/</id>
<published>2018-11-06T16:30:00.000Z</published>
<updated>2018-11-06T16:37:10.854Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P3853" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>一道比较简单的二分答案题。。。</p><p>好像和跳石头区别不大。。。直接上代码就好了。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> l,n,k,pos[<span class="number">100001</span>],t_pos[<span class="number">100001</span>];</span><br><span class="line"><span class="function"><span class="keyword">bool</span> <span class="title">judge</span><span class="params">(<span class="keyword">int</span> maxx)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="built_in">memcpy</span>(t_pos,pos,<span class="keyword">sizeof</span> pos);</span><br><span class="line"> <span class="keyword">int</span> temp=<span class="number">0</span>;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">while</span>(t_pos[i]-t_pos[i<span class="number">-1</span>]>maxx)</span><br><span class="line"> {</span><br><span class="line"> ++temp;</span><br><span class="line"> t_pos[i<span class="number">-1</span>]+=maxx;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(temp>k)</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> l=read();n=read();k=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> pos[i]=read();</span><br><span class="line"> <span class="keyword">int</span> ll=<span class="number">1</span>,rr=l,mid,ans;</span><br><span class="line"> <span class="keyword">while</span>(ll<=rr)</span><br><span class="line"> {</span><br><span class="line"> mid=ll+((rr-ll)>><span class="number">1</span>);</span><br><span class="line"> <span class="keyword">if</span>(judge(mid))</span><br><span class="line"> {</span><br><span class="line"> ans=mid;</span><br><span class="line"> rr=mid<span class="number">-1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> ll=mid+<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">cout</span><<ans;</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P3853" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="二分答案" scheme="http://www.sxyoi.cn/tags/%E4%BA%8C%E5%88%86%E7%AD%94%E6%A1%88/"/>
</entry>
<entry>
<title>叠积木</title>
<link href="http://www.sxyoi.cn/2018/11/07/%E5%8F%A0%E7%A7%AF%E6%9C%A8/"/>
<id>http://www.sxyoi.cn/2018/11/07/叠积木/</id>
<published>2018-11-06T16:11:00.000Z</published>
<updated>2018-11-06T16:22:49.753Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P2342" target="_blank" rel="noopener">题目链接</a></p><p>一道不错的带权并查集入门题</p><a id="more"></a><h2>sol</h2><p>用两个并查集来做</p><p>a[]以积木底部的积木为根，带权，用于统计操作</p><p>b[]以积木顶部党的积木为根，不带权，用于移动操作</p><p>移动的时候，a并查集把x底部的接到y顶部的，也就是把a[x]的根接到b[y]的根上，b并查集把y顶部的接到x底部的，也就是把b[y]的根接到a[x]上</p><p>权值相应的搞一搞就行了，好像这个并不是重点？</p><p>但是权值在询问的时候应该要先finda()一下把它路径压缩一下，否则我认为可能它并没有直接连到根上，从而使得其权值并非到根的权值而只是一个到其父节点（非根）的权值</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 30001</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> a[MAXN],b[MAXN],v[MAXN];<span class="comment">//bottom , top , value</span></span><br><span class="line"><span class="keyword">int</span> ans;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">finda</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">if</span>(a[x])</span><br><span class="line"> {</span><br><span class="line"> a[x]=finda(a[x]);</span><br><span class="line"> ans+=v[x];</span><br><span class="line"> v[x]=ans;</span><br><span class="line"> <span class="keyword">return</span> a[x];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> <span class="keyword">return</span> x;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">findb</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> b[x]?b[x]=findb(b[x]):x;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">merge</span><span class="params">(<span class="keyword">int</span> from,<span class="keyword">int</span> to)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> to=findb(to);</span><br><span class="line"> from=finda(from);</span><br><span class="line"> v[from]=<span class="number">1</span>;</span><br><span class="line"> a[from]=to;</span><br><span class="line"> b[to]=from;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">int</span> p,tx,ty;</span><br><span class="line"> p=read();</span><br><span class="line"> rep(k,<span class="number">1</span>,p)</span><br><span class="line"> {</span><br><span class="line"> ans=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'C'</span>)<span class="comment">//query</span></span><br><span class="line"> {</span><br><span class="line"> tx=read();</span><br><span class="line"> finda(tx);</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d\n"</span>,ans);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span><span class="comment">//move</span></span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> merge(tx,ty);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P2342" target="_blank" rel="noopener">题目链接</a></p>
<p>一道不错的带权并查集入门题</p>
</summary>
<category term="并查集" scheme="http://www.sxyoi.cn/tags/%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
<category term="带权并查集" scheme="http://www.sxyoi.cn/tags/%E5%B8%A6%E6%9D%83%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
</entry>
<entry>
<title>关押罪犯</title>
<link href="http://www.sxyoi.cn/2018/11/06/%E5%85%B3%E6%8A%BC%E7%BD%AA%E7%8A%AF/"/>
<id>http://www.sxyoi.cn/2018/11/06/关押罪犯/</id>
<published>2018-11-06T15:58:00.000Z</published>
<updated>2018-11-06T16:11:09.300Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1525" target="_blank" rel="noopener">题目链接</a></p><p>一道不错的题</p><a id="more"></a><h2>sol</h2><h3>1.二分答案+二分图判定</h3><p>我们要让冲突事件影响力最大值最小，然后就容易想到二分答案</p><p>但是怎么判定？</p><p>其实两个监狱类似于两个集合，每个犯人类似于一个点，冲突关系类似于边</p><p>如果冲突最大值为maxx，就意味着对于权值大于maxx的边及其两端的点构成的子图构成了一个二分图</p><p>所以判定只是判定是否为二分图。。。直接染色判定就好了</p><p>复杂度大概是O((n+m) log max{c_i})的？</p><h3>2.并查集（虚点并查集或带权并查集）</h3><p>只会虚点并查集的做法。。。不过好像带权并查集的题有一部分可以用虚点并查集来做？还是说所有？并不怎么会带权并查集啊。。。</p><p>好像NOI食物链那道题也可以用虚点并查集来做？</p><p>用i+n表示与i敌对的点的集合，类似于一个补集</p><p>然后用类似kruskal最大生成树的方式，先处理掉影响力大的冲突关系，最后出现无法解决的矛盾时直接跳出，否则merge(u+n,v) , merge(u,v+n)</p><p>但是不知道为什么带上按秩合并一直MLE，不带按秩合并就A了。。。玄学吗？</p><p>说起来，代码长度和复杂度上好像都是并查集要更加优秀。。。但是思维难度上貌似是二分答案+二分图判定更加简单？我自己应该是想不出来虚点并查集这种操作。。。</p><h2>Code</h2><h3>1.</h3><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdlib></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> from,to,next,v;</span><br><span class="line">}e[<span class="number">200001</span>];</span><br><span class="line"><span class="keyword">int</span> last[<span class="number">20001</span>],col[<span class="number">20001</span>],<span class="keyword">ans_t</span>;</span><br><span class="line"><span class="keyword">int</span> vv[<span class="number">100001</span>];</span><br><span class="line"><span class="keyword">int</span> b[<span class="number">3</span>]={<span class="number">0</span>,<span class="number">2</span>,<span class="number">1</span>};</span><br><span class="line"><span class="keyword">int</span> n,m,cnt;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">int</span> from,<span class="keyword">int</span> to,<span class="keyword">int</span> v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">bool</span> <span class="title">dfs</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> <span class="keyword">col_t</span>)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> col[x]=<span class="keyword">col_t</span>;</span><br><span class="line"> temp=last[x];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(e[temp].v<=<span class="keyword">ans_t</span>)</span><br><span class="line"> {</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> <span class="keyword">continue</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(!col[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!dfs(e[temp].to,b[<span class="keyword">col_t</span>]))</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(b[<span class="keyword">col_t</span>]!=col[e[temp].to])</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">bool</span> <span class="title">judge</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="built_in">memset</span>(col,<span class="number">0</span>,<span class="keyword">sizeof</span> col);</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> <span class="keyword">if</span>(!col[i])</span><br><span class="line"> <span class="keyword">if</span>(!dfs(i,<span class="number">1</span>))</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> l,r,mid,ans;</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> l=<span class="number">0</span>;r=m;</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz);</span><br><span class="line"> add(ty,tx,tz);</span><br><span class="line"> vv[i]=tz;</span><br><span class="line"> }</span><br><span class="line"> sort(vv+<span class="number">1</span>,vv+m+<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(l<=r)</span><br><span class="line"> {</span><br><span class="line"> mid=((l+r)>><span class="number">1</span>);</span><br><span class="line"> <span class="keyword">ans_t</span>=vv[mid];</span><br><span class="line"> <span class="keyword">if</span>(judge())</span><br><span class="line"> {</span><br><span class="line"> r=mid<span class="number">-1</span>;</span><br><span class="line"> ans=vv[mid];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> l=mid+<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure><h3>2.</h3><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> from,to,v;</span><br><span class="line">}e[<span class="number">100001</span>];</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="keyword">int</span> fa[<span class="number">40001</span>];</span><br><span class="line"><span class="function"><span class="keyword">bool</span> <span class="title">cmp</span><span class="params">(Edge a,Edge b)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> a.v>b.v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">find</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> fa[x]==x?x:fa[x]=find(fa[x]);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">merge</span><span class="params">(<span class="keyword">int</span> x,<span class="keyword">int</span> y)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> x=find(x);y=find(y);</span><br><span class="line"> fa[x]=y;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> ans=<span class="number">0</span>;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n+n)fa[i]=i;</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> e[i].from=read();e[i].to=read();e[i].v=read();</span><br><span class="line"> }</span><br><span class="line"> sort(e+<span class="number">1</span>,e+m+<span class="number">1</span>,cmp);</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(find(e[i].from)==find(e[i].to))</span><br><span class="line"> {</span><br><span class="line"> ans=e[i].v;</span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> }</span><br><span class="line"> merge(e[i].from+n,e[i].to);</span><br><span class="line"> merge(e[i].from,e[i].to+n);</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1525" target="_blank" rel="noopener">题目链接</a></p>
<p>一道不错的题</p>
</summary>
<category term="图论" scheme="http://www.sxyoi.cn/tags/%E5%9B%BE%E8%AE%BA/"/>
<category term="二分答案" scheme="http://www.sxyoi.cn/tags/%E4%BA%8C%E5%88%86%E7%AD%94%E6%A1%88/"/>
<category term="并查集" scheme="http://www.sxyoi.cn/tags/%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
<category term="二分图" scheme="http://www.sxyoi.cn/tags/%E4%BA%8C%E5%88%86%E5%9B%BE/"/>
<category term="虚点并查集" scheme="http://www.sxyoi.cn/tags/%E8%99%9A%E7%82%B9%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
<category term="带权并查集" scheme="http://www.sxyoi.cn/tags/%E5%B8%A6%E6%9D%83%E5%B9%B6%E6%9F%A5%E9%9B%86/"/>
</entry>
<entry>
<title>HAOI2006受欢迎的牛</title>
<link href="http://www.sxyoi.cn/2018/11/06/HAOI2006%E5%8F%97%E6%AC%A2%E8%BF%8E%E7%9A%84%E7%89%9B/"/>
<id>http://www.sxyoi.cn/2018/11/06/HAOI2006受欢迎的牛/</id>
<published>2018-11-06T15:47:00.000Z</published>
<updated>2018-11-06T15:56:13.796Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P2341" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>基本操作，先把强联通分量缩成点</p><p>然后我们观察一下发现，如果一个强连通分量里的牛为明星牛，那么这个强联通分量在缩点之后的图上的出度一定为0，否则这个强连通分量不是强连通分量，而是可以与指向的那个合并，因为互相喜欢</p><p>但同时，这个明星强联通分量只能有一个，否则说明强联通分量不被其他所有强联通分量喜欢，也就是ans=0</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><vector></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><stack></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 10010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="built_in">vector</span><<span class="keyword">int</span>> G[MAXN],G2[MAXN];</span><br><span class="line"><span class="built_in">stack</span><<span class="keyword">int</span>> s;</span><br><span class="line"><span class="keyword">int</span> dfn[MAXN],low[MAXN],colcnt,col[MAXN],colnum[MAXN],ncnt,indeg[MAXN];</span><br><span class="line"><span class="keyword">bool</span> ins[MAXN],ned[MAXN];</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">paint</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> s.pop();</span><br><span class="line"> ins[x]=<span class="number">0</span>;</span><br><span class="line"> col[x]=colcnt;</span><br><span class="line"> colnum[colcnt]++;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">tarjan</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> dfn[x]=low[x]=++ncnt;</span><br><span class="line"> s.push(x);</span><br><span class="line"> ins[x]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i<G[x].size();++i)</span><br><span class="line"> {</span><br><span class="line"> temp=G[x][i];</span><br><span class="line"> <span class="keyword">if</span>(!dfn[temp])</span><br><span class="line"> {</span><br><span class="line"> tarjan(temp);</span><br><span class="line"> low[x]=min(low[x],low[temp]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(ins[temp])</span><br><span class="line"> low[x]=min(low[x],low[temp]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(low[x]==dfn[x])</span><br><span class="line"> {</span><br><span class="line"> ++colcnt;</span><br><span class="line"> <span class="keyword">while</span>((temp=s.top())!=x)</span><br><span class="line"> paint(temp);</span><br><span class="line"> paint(temp);</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,ans=<span class="number">0</span>;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> G[tx].push_back(ty);</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> <span class="keyword">if</span>(!dfn[i])</span><br><span class="line"> tarjan(i);</span><br><span class="line"> <span class="keyword">if</span>(colcnt==<span class="number">1</span>)</span><br><span class="line"> {</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,n);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,n)<span class="comment">//缩点 </span></span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> j=<span class="number">0</span>;j<G[i].size();++j)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(col[G[i][j]]!=col[i])</span><br><span class="line"> {</span><br><span class="line"> G2[col[i]].push_back(col[G[i][j]]);</span><br><span class="line"> ned[col[i]]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,colcnt)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(ans&&!ned[i])</span><br><span class="line"> {</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"0"</span>);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(!ned[i])</span><br><span class="line"> ans+=colnum[i];</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P2341" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="图论" scheme="http://www.sxyoi.cn/tags/%E5%9B%BE%E8%AE%BA/"/>
<category term="tarjan" scheme="http://www.sxyoi.cn/tags/tarjan/"/>
<category term="缩点" scheme="http://www.sxyoi.cn/tags/%E7%BC%A9%E7%82%B9/"/>
<category term="强连通分量" scheme="http://www.sxyoi.cn/tags/%E5%BC%BA%E8%BF%9E%E9%80%9A%E5%88%86%E9%87%8F/"/>
</entry>
<entry>
<title>序列合并</title>
<link href="http://www.sxyoi.cn/2018/11/06/%E5%BA%8F%E5%88%97%E5%90%88%E5%B9%B6/"/>
<id>http://www.sxyoi.cn/2018/11/06/序列合并/</id>
<published>2018-11-06T15:44:00.000Z</published>
<updated>2018-11-06T15:47:51.718Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1631" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>基本相当于《最小函数值》的弱化版</p><p>先把a,b排序，然后把a[1]和b[1~n]的加到堆里</p><p>然后枚举，并且在a[i]+b[j]>=堆顶元素时切换到下一个</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 100010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line">priority_queue<<span class="keyword">int</span>> q;</span><br><span class="line"><span class="keyword">int</span> a[MAXN],b[MAXN],ans[MAXN],n,cnt;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> n=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)a[i]=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)b[i]=read();</span><br><span class="line"> sort(a+<span class="number">1</span>,a+n+<span class="number">1</span>);</span><br><span class="line"> sort(b+<span class="number">1</span>,b+n+<span class="number">1</span>);</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> q.push(a[<span class="number">1</span>]+b[i]);</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> {</span><br><span class="line"> rep(j,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(a[i]+b[j]<q.top())</span><br><span class="line"> {</span><br><span class="line"> q.pop();</span><br><span class="line"> q.push(a[i]+b[j]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> ans[++cnt]=q.top();</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(cnt)</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d "</span>,ans[cnt--]);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1631" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="贪心" scheme="http://www.sxyoi.cn/tags/%E8%B4%AA%E5%BF%83/"/>
<category term="堆" scheme="http://www.sxyoi.cn/tags/%E5%A0%86/"/>
</entry>
<entry>
<title>最小函数值</title>
<link href="http://www.sxyoi.cn/2018/11/06/%E6%9C%80%E5%B0%8F%E5%87%BD%E6%95%B0%E5%80%BC/"/>
<id>http://www.sxyoi.cn/2018/11/06/最小函数值/</id>
<published>2018-11-06T15:35:00.000Z</published>
<updated>2018-11-06T15:44:05.676Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P2085" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>维护一个大根堆，如果当前函数在x=j的值小于堆顶元素，弹掉堆顶，加入当前值</p><p>如果当前函数在x=j的值大于等于堆顶元素并且在x=j的导数值大于上一个函数在x=j的导数值，说明这个函数后面也不会比之前的函数更优，直接换到下一个函数即可</p><p>发现有了这种求前k大值得方法好像快排求前k大就比较鸡肋啊。。。？不知道是不是还有其他用途，毕竟快排是个分治算法。。。就像线性筛不能完全替代埃氏筛？</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 10010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line">priority_queue<<span class="keyword">int</span>> q;</span><br><span class="line"><span class="keyword">int</span> a[MAXN],b[MAXN],c[MAXN],n,m;</span><br><span class="line"><span class="keyword">int</span> ans[MAXN],cnt;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> a[i]=read();b[i]=read();c[i]=read();</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,m)q.push(a[<span class="number">1</span>]*i*i+b[<span class="number">1</span>]*i+c[<span class="number">1</span>]);</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> {</span><br><span class="line"> rep(j,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> temp=a[i]*j*j+b[i]*j+c[i];</span><br><span class="line"> <span class="keyword">if</span>(temp<q.top())</span><br><span class="line"> {</span><br><span class="line"> q.pop();</span><br><span class="line"> q.push(temp);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(<span class="number">2</span>*a[i]*j+b[i]>=<span class="number">2</span>*a[i<span class="number">-1</span>]*j+b[i<span class="number">-1</span>])</span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> ans[++cnt]=q.top();</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(cnt)</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d "</span>,ans[cnt--]);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P2085" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="堆" scheme="http://www.sxyoi.cn/tags/%E5%A0%86/"/>
<category term="导数" scheme="http://www.sxyoi.cn/tags/%E5%AF%BC%E6%95%B0/"/>
</entry>
<entry>
<title>HAOI2009巧克力&矩形分割</title>
<link href="http://www.sxyoi.cn/2018/11/06/HAOI2009%E5%B7%A7%E5%85%8B%E5%8A%9B&%E7%9F%A9%E5%BD%A2%E5%88%86%E5%89%B2/"/>
<id>http://www.sxyoi.cn/2018/11/06/HAOI2009巧克力&矩形分割/</id>
<published>2018-11-06T15:23:00.000Z</published>
<updated>2018-11-06T15:33:44.704Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P3173" target="_blank" rel="noopener">HAOI2009巧克力</a></p><p><a href="https://www.luogu.org/problemnew/show/P1324" target="_blank" rel="noopener">矩形分割</a></p><a id="more"></a><h2>sol</h2><p>不难想到一个O(nm)的dp（应该是正确的。。。）</p><p>但是显然复杂度过不去</p><p>然后发现贪心就可以。。。</p><p>其实x和y切割线权值跟线的位置编号是无关的。。。所以可以sort一遍</p><p>然后考虑切的策略，如果先切权值小的，那么权值大的放到后面对切割花费的贡献会更大，花费总和也就会更大，所以我们先切大的即可。。。</p><p>现在做贪心题总感觉贪心不对。。。除非是在知道这个题贪心可做的情况下才敢信心满满的去打贪心。。。以后还是先要考虑一下贪心再去考虑其他dp之类的做法。。。除非有什么不满足贪心性质的地方再去想什么dp之类的。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 10010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">bool</span> <span class="title">cmp</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &a,<span class="keyword">const</span> <span class="keyword">int</span> &b)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">return</span> a>b;</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> x[MAXN],y[MAXN],n,m;</span><br><span class="line"><span class="keyword">long</span> <span class="keyword">long</span> ans;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> l=<span class="number">1</span>,r=<span class="number">1</span>;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i<n;++i)x[i]=read();</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i<m;++i)y[i]=read();</span><br><span class="line"> sort(x+<span class="number">1</span>,x+n,cmp);sort(y+<span class="number">1</span>,y+m,cmp);</span><br><span class="line"> <span class="keyword">while</span>(l<n&&r<m)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(x[l]>y[r])</span><br><span class="line"> {</span><br><span class="line"> ans+=x[l]*r;</span><br><span class="line"> ++l;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> {</span><br><span class="line"> ans+=y[r]*l;</span><br><span class="line"> ++r;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(l<n)</span><br><span class="line"> {</span><br><span class="line"> ans+=x[l]*r;++l;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(r<m)</span><br><span class="line"> {</span><br><span class="line"> ans+=y[r]*l;++r;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">cout</span><<ans;</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P3173" target="_blank" rel="noopener">HAOI2009巧克力</a></p>
<p><a href="https://www.luogu.org/problemnew/show/P1324" target="_blank" rel="noopener">矩形分割</a></p>
</summary>
<category term="贪心" scheme="http://www.sxyoi.cn/tags/%E8%B4%AA%E5%BF%83/"/>
</entry>
<entry>
<title>相似基因</title>
<link href="http://www.sxyoi.cn/2018/11/06/%E7%9B%B8%E4%BC%BC%E5%9F%BA%E5%9B%A0/"/>
<id>http://www.sxyoi.cn/2018/11/06/相似基因/</id>
<published>2018-11-06T15:13:00.000Z</published>
<updated>2018-11-06T15:23:45.319Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1140" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>总是想做成一维的，但是发现做不出</p><p>dp[i]/[j]表示第一串到第i位，第二串到第j位的最大相似度</p><p>然后不难发现可以从(i,j-1) / (i-1,j) / (i-1,j-1)转移过来</p><p>//但是不知道为什么从(0,0)开始 往后推不对，就是从(i,j)到(i)</p><p>↑错误的原因是没有(len1,len2)从(len1-1,len2)和(len1,len2-1)转移过来的情况，居然想了一个小时都没想出来为什么错。。。写这篇博客的时候重新写了一下三种转移恍然大悟。。。稍微改动一下就可以ac了。。。</p><p>WA的转移</p><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i<l1;++i)</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> j=<span class="number">0</span>;j<l2;++j)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=max(dp[i+<span class="number">1</span>][j+<span class="number">1</span>],mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]]+dp[i][j]);</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][<span class="number">0</span>]; </span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j]=max(dp[i+<span class="number">1</span>][j],mapp[ja[i+<span class="number">1</span>]][<span class="number">0</span>]+dp[i][j]);</span><br><span class="line"> <span class="keyword">if</span>(!vis[i][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i][j+<span class="number">1</span>]=dp[i][j]+mapp[<span class="number">0</span>][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i][j+<span class="number">1</span>]=max(dp[i][j+<span class="number">1</span>],dp[i][j]+mapp[<span class="number">0</span>][jb[j+<span class="number">1</span>]]);</span><br><span class="line"> }</span><br></pre></td></tr></table></figure><p>正确的转移</p><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i<=l1;++i)</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> j=<span class="number">0</span>;j<=l2;++j)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(i+<span class="number">1</span><=l1&&j+<span class="number">1</span><=l2)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=max(dp[i+<span class="number">1</span>][j+<span class="number">1</span>],mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]]+dp[i][j]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(i+<span class="number">1</span><=l1)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][<span class="number">4</span>]; </span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j]=max(dp[i+<span class="number">1</span>][j],mapp[ja[i+<span class="number">1</span>]][<span class="number">4</span>]+dp[i][j]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(j+<span class="number">1</span><=l2)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i][j+<span class="number">1</span>]=dp[i][j]+mapp[<span class="number">4</span>][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i][j+<span class="number">1</span>]=max(dp[i][j+<span class="number">1</span>],dp[i][j]+mapp[<span class="number">4</span>][jb[j+<span class="number">1</span>]]);</span><br><span class="line"> }</span><br><span class="line"> }</span><br></pre></td></tr></table></figure><p>并不喜欢题解里的从当前的减去那种转移方式。。。感觉初始化不好想，而且在这里感觉没那么直观显然。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="keyword">const</span> <span class="keyword">int</span> mapp[<span class="number">5</span>][<span class="number">5</span>]=</span><br><span class="line">{</span><br><span class="line"> {<span class="number">5</span>,<span class="number">-1</span>,<span class="number">-2</span>,<span class="number">-1</span>,<span class="number">-3</span>},</span><br><span class="line"> {<span class="number">-1</span>,<span class="number">5</span>,<span class="number">-3</span>,<span class="number">-2</span>,<span class="number">-4</span>},</span><br><span class="line"> {<span class="number">-2</span>,<span class="number">-3</span>,<span class="number">5</span>,<span class="number">-2</span>,<span class="number">-2</span>},</span><br><span class="line"> {<span class="number">-1</span>,<span class="number">-2</span>,<span class="number">-2</span>,<span class="number">5</span>,<span class="number">-1</span>},</span><br><span class="line"> {<span class="number">-3</span>,<span class="number">-4</span>,<span class="number">-2</span>,<span class="number">-1</span>,<span class="number">0</span>}</span><br><span class="line">};</span><br><span class="line"><span class="keyword">int</span> dp[<span class="number">101</span>][<span class="number">101</span>];</span><br><span class="line"><span class="keyword">int</span> l1,l2,ja[<span class="number">101</span>],jb[<span class="number">101</span>];</span><br><span class="line"><span class="keyword">bool</span> vis[<span class="number">101</span>][<span class="number">101</span>];</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="built_in">scanf</span>(<span class="string">"%d"</span>,&l1);</span><br><span class="line"> rep(i,<span class="number">1</span>,l1)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'A'</span>)ja[i]=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'C'</span>)ja[i]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'G'</span>)ja[i]=<span class="number">2</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'T'</span>)ja[i]=<span class="number">3</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">scanf</span>(<span class="string">"%d"</span>,&l2);</span><br><span class="line"> rep(i,<span class="number">1</span>,l2)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'A'</span>)jb[i]=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'C'</span>)jb[i]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'G'</span>)jb[i]=<span class="number">2</span>;</span><br><span class="line"> <span class="keyword">else</span> <span class="keyword">if</span>(c==<span class="string">'T'</span>)jb[i]=<span class="number">3</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">0</span>;i<=l1;++i)</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> j=<span class="number">0</span>;j<=l2;++j)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(i+<span class="number">1</span><=l1&&j+<span class="number">1</span><=l2)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j+<span class="number">1</span>]=max(dp[i+<span class="number">1</span>][j+<span class="number">1</span>],mapp[ja[i+<span class="number">1</span>]][jb[j+<span class="number">1</span>]]+dp[i][j]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(i+<span class="number">1</span><=l1)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i+<span class="number">1</span>][j])</span><br><span class="line"> {</span><br><span class="line"> vis[i+<span class="number">1</span>][j]=<span class="number">1</span>;</span><br><span class="line"> dp[i+<span class="number">1</span>][j]=dp[i][j]+mapp[ja[i+<span class="number">1</span>]][<span class="number">4</span>]; </span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i+<span class="number">1</span>][j]=max(dp[i+<span class="number">1</span>][j],mapp[ja[i+<span class="number">1</span>]][<span class="number">4</span>]+dp[i][j]);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(j+<span class="number">1</span><=l2)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!vis[i][j+<span class="number">1</span>])</span><br><span class="line"> {</span><br><span class="line"> vis[i][j+<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> dp[i][j+<span class="number">1</span>]=dp[i][j]+mapp[<span class="number">4</span>][jb[j+<span class="number">1</span>]];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> dp[i][j+<span class="number">1</span>]=max(dp[i][j+<span class="number">1</span>],dp[i][j]+mapp[<span class="number">4</span>][jb[j+<span class="number">1</span>]]);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">cout</span><<dp[l1][l2];</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1140" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="动态规划" scheme="http://www.sxyoi.cn/tags/%E5%8A%A8%E6%80%81%E8%A7%84%E5%88%92/"/>
</entry>
<entry>
<title>【USACO07JAN】区间统计Tallest Cow</title>
<link href="http://www.sxyoi.cn/2018/11/06/%5BUSACO07JAN%5D%E5%8C%BA%E9%97%B4%E7%BB%9F%E8%AE%A1Tallest%20Cow/"/>
<id>http://www.sxyoi.cn/2018/11/06/[USACO07JAN]区间统计Tallest Cow/</id>
<published>2018-11-06T15:08:00.000Z</published>
<updated>2018-11-06T15:12:31.254Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P2879" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>一开始以为是个线段树或者分块之类的数据结构，但是对于最后的输出并不是很好</p><p>然后发现可以差分</p><p>一开始所有的身高都是可能的最大身高，每当出现一对(a,b)相望时，[a+1,b-1]中的身高-1</p><p>注意到会有重复数据，所以要判重</p><p>直接用了个map做掉了。。。</p><p>不判重就只有五十分。。。以后还是要考虑一下数据的问题。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><map></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> cf[<span class="number">10010</span>];</span><br><span class="line"><span class="built_in">map</span><<span class="keyword">int</span>,<span class="keyword">int</span>> sb;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty;</span><br><span class="line"> <span class="keyword">int</span> n=read(),I=read(),Mh=read(),r=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,r)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> <span class="keyword">if</span>(tx>ty)swap(tx,ty);</span><br><span class="line"> <span class="keyword">if</span>(ty-tx<=<span class="number">1</span>)<span class="keyword">continue</span>;</span><br><span class="line"> <span class="keyword">if</span>(sb[tx*n+ty])<span class="keyword">continue</span>;</span><br><span class="line"> sb[tx*n+ty]=<span class="number">1</span>;</span><br><span class="line"> cf[tx]-=<span class="number">1</span>;</span><br><span class="line"> cf[ty<span class="number">-1</span>]+=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d\n"</span>,Mh);</span><br><span class="line"> Mh+=cf[i];</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P2879" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="差分" scheme="http://www.sxyoi.cn/tags/%E5%B7%AE%E5%88%86/"/>
<category term="哈希判重" scheme="http://www.sxyoi.cn/tags/%E5%93%88%E5%B8%8C%E5%88%A4%E9%87%8D/"/>
</entry>
<entry>
<title>JLOI2012树</title>
<link href="http://www.sxyoi.cn/2018/11/06/JLOI2012%E6%A0%91/"/>
<id>http://www.sxyoi.cn/2018/11/06/JLOI2012树/</id>
<published>2018-11-06T14:58:00.000Z</published>
<updated>2018-11-06T15:07:02.200Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P3252" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>一开始以为树形dp什么的。。。但是是多叉树就不会了。。。</p><p>然后想的是： dfs，每搜到一个叶子节点就开始在栈内节点上尺取（好像也叫two-pointers）？但是并不会打尺取/two-pointers</p><p>所以就每次搜到叶子做一个前缀和，然后对于每一个找</p><p>是否存在summ[j]，使得summ[now]-summ[j]==S</p><p>然后注意到点权都是正整数，所以可以二分查找</p><p>但这个复杂度好像并不对，最坏应该是O( (n^2) * (log n -log 4) / 4) ，是n^2 log n级别的了，但是题目好像并没有卡</p><p>如果尺取的话复杂度的log应该就没了，也就n^2级别，只是常数比下面的搜索小一点？</p><p>其实从每个点开始dfs的最坏复杂度也就O(n^2 / 2) ，就是n^2级别的了</p><p>所以感觉这两种并不是正解？</p><p>但是并不会其他做法。。。我好菜啊。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> MAXN 100010</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next;</span><br><span class="line">}e[MAXN];</span><br><span class="line"><span class="keyword">int</span> last[MAXN],dp[MAXN],v[MAXN];</span><br><span class="line"><span class="keyword">int</span> n,s,myStack[MAXN],tail,ans;</span><br><span class="line"><span class="keyword">int</span> summ[MAXN];</span><br><span class="line"><span class="keyword">bool</span> vis[MAXN],notRoot[MAXN];</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">dfs</span><span class="params">(<span class="keyword">int</span> x)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> myStack[++tail]=x;</span><br><span class="line"> <span class="keyword">if</span>(!last[x])</span><br><span class="line"> {</span><br><span class="line"> rep(i,<span class="number">1</span>,tail)</span><br><span class="line"> summ[i]=summ[i<span class="number">-1</span>]+v[myStack[i]];</span><br><span class="line"> rep(i,<span class="number">1</span>,tail)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(vis[myStack[i]])</span><br><span class="line"> <span class="keyword">continue</span>;</span><br><span class="line"> vis[myStack[i]]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">if</span>((*lower_bound(summ,summ+i+<span class="number">1</span>,summ[i]-s))==summ[i]-s)</span><br><span class="line"> ++ans;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">else</span></span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">int</span> temp=last[x];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> dfs(e[temp].to);</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> --tail;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty;</span><br><span class="line"> n=read();s=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> v[i]=read();</span><br><span class="line"> <span class="keyword">if</span>(v[i]==s)</span><br><span class="line"> {</span><br><span class="line"> ++ans;</span><br><span class="line"> vis[i]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i=<span class="number">1</span>;i<n;++i)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> e[i].next=last[tx];</span><br><span class="line"> last[tx]=i;</span><br><span class="line"> e[i].to=ty;</span><br><span class="line"> notRoot[ty]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> <span class="keyword">if</span>(!notRoot[i])</span><br><span class="line"> {</span><br><span class="line"> dfs(i);</span><br><span class="line"> <span class="keyword">break</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%d"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P3252" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="DFS" scheme="http://www.sxyoi.cn/tags/DFS/"/>
<category term="二分查找" scheme="http://www.sxyoi.cn/tags/%E4%BA%8C%E5%88%86%E6%9F%A5%E6%89%BE/"/>
<category term="前缀和" scheme="http://www.sxyoi.cn/tags/%E5%89%8D%E7%BC%80%E5%92%8C/"/>
</entry>
<entry>
<title>树的重量(构造答案)</title>
<link href="http://www.sxyoi.cn/2018/11/06/%E6%A0%91%E7%9A%84%E9%87%8D%E9%87%8F(%E6%9E%84%E9%80%A0%E7%AD%94%E6%A1%88)/"/>
<id>http://www.sxyoi.cn/2018/11/06/树的重量(构造答案)/</id>
<published>2018-11-06T02:14:00.000Z</published>
<updated>2018-11-06T14:57:14.618Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1268" target="_blank" rel="noopener">题目链接</a></p><p>一道很不错的题</p><a id="more"></a><h2>sol</h2><p>一开始想到了最小生成树，但是后来发现k可以在图上加点，边可以重叠</p><p>然后就不会了。。。</p><p>先从小的数据开始考虑，如果有两个点，显然ans=dis[1]/[2]</p><p>在考虑3个点，有可能到3的边是从1->2上延伸出来的一条“叉边”</p><p>叉边其实是这种情况：</p><p><img src="https://cdn.luogu.org/upload/pic/42347.png" alt=""></p><p>然后1和2直接连边，枚举i=3~n找从1~i-1最小的延伸出的叉边</p><p>结合上图等价关系不难发现：叉边长度=(dis[1]/[i]+dis[j]/[i]-dis[i]/[j])/2</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"><span class="keyword">char</span> c;</span><br><span class="line"><span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"><span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"><span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"><span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line">{</span><br><span class="line">a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line">}</span><br><span class="line"><span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">int</span> dis[<span class="number">31</span>][<span class="number">31</span>],n;</span><br><span class="line"><span class="keyword">long</span> <span class="keyword">long</span> ans;</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"><span class="keyword">int</span> minn;</span><br><span class="line"><span class="keyword">while</span>(n=read())</span><br><span class="line">{</span><br><span class="line">rep(i,<span class="number">1</span>,n)</span><br><span class="line"> rep(j,i+<span class="number">1</span>,n)</span><br><span class="line"> dis[i][j]=read();</span><br><span class="line">ans=dis[<span class="number">1</span>][<span class="number">2</span>];</span><br><span class="line">rep(i,<span class="number">3</span>,n)</span><br><span class="line">{</span><br><span class="line">minn=<span class="number">2147483647</span>;</span><br><span class="line">rep(j,<span class="number">2</span>,i<span class="number">-1</span>)</span><br><span class="line"> minn=min(minn,(dis[<span class="number">1</span>][i]+dis[j][i]-dis[<span class="number">1</span>][j])/<span class="number">2</span>);</span><br><span class="line">ans+=minn;</span><br><span class="line"><span class="comment">//cout<<ans<<"test\n";</span></span><br><span class="line">}</span><br><span class="line"><span class="built_in">printf</span>(<span class="string">"%lld\n"</span>,ans);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1268" target="_blank" rel="noopener">题目链接</a></p>
<p>一道很不错的题</p>
</summary>
<category term="图论" scheme="http://www.sxyoi.cn/tags/%E5%9B%BE%E8%AE%BA/"/>
<category term="构造" scheme="http://www.sxyoi.cn/tags/%E6%9E%84%E9%80%A0/"/>
</entry>
<entry>
<title>请柬/邮递员送信（反图spfa）</title>
<link href="http://www.sxyoi.cn/2018/10/28/%E8%AF%B7%E6%9F%AC%EF%BC%8C%E9%82%AE%E9%80%92%E5%91%98%E9%80%81%E4%BF%A1/"/>
<id>http://www.sxyoi.cn/2018/10/28/请柬，邮递员送信/</id>
<published>2018-10-27T16:18:00.000Z</published>
<updated>2018-10-27T16:23:24.914Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1342" target="_blank" rel="noopener">请柬</a></p><p><a href="https://www.luogu.org/problemnew/show/P1629" target="_blank" rel="noopener">邮递员送信</a></p><a id="more"></a><h2>sol</h2><p>这两道题好像基本上是完全一样的啊。。。不知道为什么一道黄一道蓝。。。</p><p>如果是无向图要来回时间直接*2</p><p>有向图的话，显然的做法是从每个点跑一遍spfa找到起点的最短路。。。但是显然过不了</p><p>其实上面等价于在反图上跑一遍spfa</p><p>所以我们正图跑一边spfa，反图跑一边spfa，这样正图上的是1点到其他点的最短路，反图上是其他点到1点的最短路，不得不说图论真的是神奇。。。</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br><span class="line">150</span><br><span class="line">151</span><br><span class="line">152</span><br><span class="line">153</span><br><span class="line">154</span><br><span class="line">155</span><br><span class="line">156</span><br><span class="line">157</span><br><span class="line">158</span><br><span class="line">159</span><br><span class="line">160</span><br><span class="line">161</span><br><span class="line">162</span><br><span class="line">163</span><br><span class="line">164</span><br><span class="line">165</span><br><span class="line">166</span><br><span class="line">167</span><br><span class="line">168</span><br><span class="line">169</span><br><span class="line">170</span><br><span class="line">171</span><br><span class="line">172</span><br><span class="line">173</span><br><span class="line">174</span><br><span class="line">175</span><br><span class="line">176</span><br><span class="line">177</span><br><span class="line">178</span><br><span class="line">179</span><br><span class="line">180</span><br><span class="line">181</span><br><span class="line">182</span><br><span class="line">183</span><br><span class="line">184</span><br><span class="line">185</span><br><span class="line">186</span><br><span class="line">187</span><br><span class="line">188</span><br><span class="line">189</span><br><span class="line">190</span><br><span class="line">191</span><br><span class="line">192</span><br><span class="line">193</span><br><span class="line">194</span><br><span class="line">195</span><br><span class="line">196</span><br><span class="line">197</span><br><span class="line">198</span><br><span class="line">199</span><br><span class="line">200</span><br><span class="line">201</span><br><span class="line">202</span><br><span class="line">203</span><br><span class="line">204</span><br><span class="line">205</span><br><span class="line">206</span><br><span class="line">207</span><br><span class="line">208</span><br><span class="line">209</span><br><span class="line">210</span><br><span class="line">211</span><br><span class="line">212</span><br><span class="line">213</span><br><span class="line">214</span><br><span class="line">215</span><br><span class="line">216</span><br><span class="line">217</span><br><span class="line">218</span><br><span class="line">219</span><br><span class="line">220</span><br><span class="line">221</span><br><span class="line">222</span><br><span class="line">223</span><br><span class="line">224</span><br><span class="line">225</span><br><span class="line">226</span><br><span class="line">227</span><br><span class="line">228</span><br><span class="line">229</span><br><span class="line">230</span><br><span class="line">231</span><br><span class="line">232</span><br><span class="line">233</span><br><span class="line">234</span><br><span class="line">235</span><br><span class="line">236</span><br><span class="line">237</span><br><span class="line">238</span><br><span class="line">239</span><br><span class="line">240</span><br><span class="line">241</span><br><span class="line">242</span><br><span class="line">243</span><br><span class="line">244</span><br><span class="line">245</span><br><span class="line">246</span><br><span class="line">247</span><br><span class="line">248</span><br><span class="line">249</span><br><span class="line">250</span><br><span class="line">251</span><br><span class="line">252</span><br><span class="line">253</span><br><span class="line">254</span><br><span class="line">255</span><br><span class="line">256</span><br><span class="line">257</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//邮递员送信</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v;</span><br><span class="line">}e[<span class="number">100010</span>],ve[<span class="number">100010</span>];</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="keyword">int</span> last[<span class="number">1001</span>],vlast[<span class="number">1001</span>],cnt,vcnt;</span><br><span class="line"><span class="keyword">long</span> <span class="keyword">long</span> dis[<span class="number">1001</span>],vdis[<span class="number">1001</span>];</span><br><span class="line"><span class="keyword">bool</span> vis[<span class="number">1001</span>];</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">vadd</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> ve[++vcnt].next=vlast[from];</span><br><span class="line"> vlast[from]=vcnt;</span><br><span class="line"> ve[vcnt].to=to;</span><br><span class="line"> ve[vcnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">spfa</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="built_in">memset</span>(vis,<span class="number">0</span>,<span class="keyword">sizeof</span> vis);</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> dis[i]=<span class="number">-1</span>;</span><br><span class="line"> dis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> <span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> vis[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> temp=last[q.front()];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[e[temp].to]<<span class="number">0</span>||dis[e[temp].to]>dis[q.front()]+e[temp].v)</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to]=dis[q.front()]+e[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!vis[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> vis[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> vis[q.front()]=<span class="number">0</span>;</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">vspfa</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="built_in">memset</span>(vis,<span class="number">0</span>,<span class="keyword">sizeof</span> vis);</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> vdis[i]=<span class="number">-1</span>;</span><br><span class="line"> vdis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> <span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> vis[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> temp=vlast[q.front()];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(vdis[ve[temp].to]<<span class="number">0</span>||vdis[ve[temp].to]>vdis[q.front()]+ve[temp].v)</span><br><span class="line"> {</span><br><span class="line"> vdis[ve[temp].to]=vdis[q.front()]+ve[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!vis[ve[temp].to])</span><br><span class="line"> {</span><br><span class="line"> vis[ve[temp].to]=<span class="number">1</span>;</span><br><span class="line"> q.push(ve[temp].to);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=ve[temp].next;</span><br><span class="line"> }</span><br><span class="line"> vis[q.front()]=<span class="number">0</span>;</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> </span><br><span class="line"> <span class="keyword">long</span> <span class="keyword">long</span> ans=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz);</span><br><span class="line"> vadd(ty,tx,tz);</span><br><span class="line"> }</span><br><span class="line"> spfa();</span><br><span class="line"> vspfa();</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> {</span><br><span class="line"> ans+=(dis[i]+vdis[i]);</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">cout</span><<ans;</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"><span class="comment">//请柬</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><queue></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">Edge</span>{</span></span><br><span class="line"> <span class="keyword">int</span> to,next,v;</span><br><span class="line">}e[<span class="number">1000010</span>],ve[<span class="number">1000010</span>];</span><br><span class="line"><span class="keyword">int</span> n,m;</span><br><span class="line"><span class="keyword">int</span> vlast[<span class="number">1000001</span>],last[<span class="number">1000001</span>],cnt;</span><br><span class="line"><span class="keyword">long</span> <span class="keyword">long</span> dis[<span class="number">1000001</span>],ans;</span><br><span class="line"><span class="keyword">bool</span> inq[<span class="number">1000001</span>];</span><br><span class="line"><span class="built_in">queue</span><<span class="keyword">int</span>> q;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">add</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> e[++cnt].next=last[from];</span><br><span class="line"> last[from]=cnt;</span><br><span class="line"> e[cnt].to=to;</span><br><span class="line"> e[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">void</span> <span class="title">vadd</span><span class="params">(<span class="keyword">const</span> <span class="keyword">int</span> &from,<span class="keyword">const</span> <span class="keyword">int</span> &to,<span class="keyword">const</span> <span class="keyword">int</span> &v)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> ve[cnt].next=vlast[from];</span><br><span class="line"> vlast[from]=cnt;</span><br><span class="line"> ve[cnt].to=to;</span><br><span class="line"> ve[cnt].v=v;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">spfa1</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> dis[i]=<span class="number">2147483647</span>;</span><br><span class="line"> dis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> inq[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> temp=last[q.front()];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[e[temp].to]>dis[q.front()]+e[temp].v)</span><br><span class="line"> {</span><br><span class="line"> dis[e[temp].to]=dis[q.front()]+e[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!inq[e[temp].to])</span><br><span class="line"> {</span><br><span class="line"> q.push(e[temp].to);</span><br><span class="line"> inq[e[temp].to]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=e[temp].next;</span><br><span class="line"> }</span><br><span class="line"> inq[q.front()]=<span class="number">0</span>;</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">void</span> <span class="title">spfa2</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> temp;</span><br><span class="line"> rep(i,<span class="number">2</span>,n)</span><br><span class="line"> dis[i]=<span class="number">2147483647</span>;</span><br><span class="line"> dis[<span class="number">1</span>]=<span class="number">0</span>;</span><br><span class="line"> inq[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line"> q.push(<span class="number">1</span>);</span><br><span class="line"> <span class="keyword">while</span>(!q.empty())</span><br><span class="line"> {</span><br><span class="line"> temp=vlast[q.front()];</span><br><span class="line"> <span class="keyword">while</span>(temp)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[ve[temp].to]>dis[q.front()]+ve[temp].v)</span><br><span class="line"> {</span><br><span class="line"> dis[ve[temp].to]=dis[q.front()]+ve[temp].v;</span><br><span class="line"> <span class="keyword">if</span>(!inq[ve[temp].to])</span><br><span class="line"> {</span><br><span class="line"> q.push(ve[temp].to);</span><br><span class="line"> inq[ve[temp].to]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> temp=ve[temp].next;</span><br><span class="line"> }</span><br><span class="line"> inq[q.front()]=<span class="number">0</span>;</span><br><span class="line"> q.pop();</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty,tz;</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();tz=read();</span><br><span class="line"> add(tx,ty,tz);</span><br><span class="line"> vadd(ty,tx,tz);</span><br><span class="line"> }</span><br><span class="line"> spfa1();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[i]!=<span class="number">2147483647</span>)</span><br><span class="line"> ans+=dis[i];</span><br><span class="line"> }</span><br><span class="line"> spfa2();</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(dis[i]!=<span class="number">2147483647</span>)</span><br><span class="line"> ans+=dis[i];</span><br><span class="line"> }</span><br><span class="line"> <span class="built_in">printf</span>(<span class="string">"%lld"</span>,ans);</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure><h2>总结</h2>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1342" target="_blank" rel="noopener">请柬</a></p>
<p><a href="https://www.luogu.org/problemnew/show/P1629" target="_blank" rel="noopener">邮递员送信</a></p>
</summary>
<category term="图论" scheme="http://www.sxyoi.cn/tags/%E5%9B%BE%E8%AE%BA/"/>
<category term="最短路" scheme="http://www.sxyoi.cn/tags/%E6%9C%80%E7%9F%AD%E8%B7%AF/"/>
</entry>
<entry>
<title>跑路</title>
<link href="http://www.sxyoi.cn/2018/10/28/%E8%B7%91%E8%B7%AF/"/>
<id>http://www.sxyoi.cn/2018/10/28/跑路/</id>
<published>2018-10-27T16:09:00.000Z</published>
<updated>2018-10-27T16:16:38.657Z</updated>
<content type="html"><![CDATA[<p><a href="https://www.luogu.org/problemnew/show/P1613" target="_blank" rel="noopener">题目链接</a></p><a id="more"></a><h2>sol</h2><p>这道题是最短路径和倍增思想的结合题。</p><p>观察到每条边长度均为1km，也就是2^0</p><p>再观察跑路器，每秒钟可以跑2^k千米</p><p>所以用倍增，如果u，v之间存在一条路径长度为2^k千米，那么可以转化为它们之间存在一条消耗时间为1的边</p><p>如果u，v之间存在一个点w， u，w之间存在一条路径长度为2^k，w，v之间存在一条路径长度为2^k，那么u，v之间存在一条长度为2^{k+1}的路径，当然也是消耗时间为1</p><p>按这个方法跑一边floyd来建图，然后再跑一遍Floyd找最短路径即可</p><h2>Code</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><iostream></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstring></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cstdio></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><cmath></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> rep(i,l,r) for(int i=l;i<=r;++i)</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> per(i,l,r) for(int i=l;i>=r;--i)</span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="built_in">std</span>;</span><br><span class="line"><span class="function"><span class="keyword">inline</span> <span class="keyword">int</span> <span class="title">read</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">char</span> c;</span><br><span class="line"> <span class="keyword">bool</span> t=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">int</span> a=<span class="number">0</span>;</span><br><span class="line"> <span class="keyword">while</span>((c=getchar())==<span class="string">' '</span>||c==<span class="string">'\n'</span>||c==<span class="string">'\r'</span>);</span><br><span class="line"> <span class="keyword">if</span>(c==<span class="string">'-'</span>)</span><br><span class="line"> {</span><br><span class="line"> t=<span class="number">1</span>;c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">while</span>(c>=<span class="string">'0'</span>&&c<=<span class="string">'9'</span>)</span><br><span class="line"> {</span><br><span class="line"> a*=<span class="number">10</span>;a+=(c-<span class="string">'0'</span>);c=getchar();</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> a*(t?<span class="number">-1</span>:<span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"><span class="keyword">bool</span> dp[<span class="number">70</span>][<span class="number">51</span>][<span class="number">51</span>];</span><br><span class="line"><span class="keyword">int</span> n,m,dis[<span class="number">51</span>][<span class="number">51</span>];</span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line"> <span class="keyword">int</span> tx,ty;</span><br><span class="line"> <span class="built_in">memset</span>(dis,<span class="number">0x3f3f3f3f</span>,<span class="keyword">sizeof</span> dis);</span><br><span class="line"> n=read();m=read();</span><br><span class="line"> rep(i,<span class="number">1</span>,m)</span><br><span class="line"> {</span><br><span class="line"> tx=read();ty=read();</span><br><span class="line"> dp[<span class="number">0</span>][tx][ty]=<span class="number">1</span>;</span><br><span class="line"> dis[tx][ty]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(w,<span class="number">1</span>,<span class="number">64</span>)</span><br><span class="line"> rep(k,<span class="number">1</span>,n)</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> rep(j,<span class="number">1</span>,n)</span><br><span class="line"> {</span><br><span class="line"> <span class="keyword">if</span>(!dp[w][i][j])</span><br><span class="line"> dp[w][i][j]=(dp[w<span class="number">-1</span>][i][k]&dp[w<span class="number">-1</span>][k][j]);</span><br><span class="line"> <span class="keyword">if</span>(dp[w][i][j])</span><br><span class="line"> dis[i][j]=<span class="number">1</span>;</span><br><span class="line"> }</span><br><span class="line"> rep(k,<span class="number">1</span>,n)</span><br><span class="line"> rep(i,<span class="number">1</span>,n)</span><br><span class="line"> rep(j,<span class="number">1</span>,n)</span><br><span class="line"> dis[i][j]=min(dis[i][j],dis[i][k]+dis[k][j]);</span><br><span class="line"> <span class="built_in">cout</span><<dis[<span class="number">1</span>][n];</span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure><h2>总结</h2><p>神奇的操作。。。</p>]]></content>
<summary type="html">
<p><a href="https://www.luogu.org/problemnew/show/P1613" target="_blank" rel="noopener">题目链接</a></p>
</summary>
<category term="最短路" scheme="http://www.sxyoi.cn/tags/%E6%9C%80%E7%9F%AD%E8%B7%AF/"/>
<category term="Floyd" scheme="http://www.sxyoi.cn/tags/Floyd/"/>
<category term="倍增" scheme="http://www.sxyoi.cn/tags/%E5%80%8D%E5%A2%9E/"/>
</entry>
</feed>