Java Algorithm Problems

前戏

To host Java Solutions to algorithm problems from LintCode, LeetCode...etc. I Will try to revise the solutions once new problem or new testing case occurs. Mid 2016 I realize that people may want to contribute to this repo, and make it better by contributing fixes, better solutions ... etc. Free free to send pull request. Once verified, I'm happy to merge in! CALM DOWN AND CODE ON! Fellows!

News

2017年1月17日, 陪我征战多年的 2014 MackBookPro i7 3.xGHz 被一杯清水结束了生命，在这里深切缅怀悼念。这个Git Repo是小M陪我一字一句打出来的，有过蹉跎，也有过辉煌，陪我从Day1刷题一直刷到了Day1之中。直至今日，小M记录的代码还在给广大coder带来福利。为了延续小M无私奉献的精神,我将重新在这个repo活跃起来，重整已有的问题，也会尝试总结一些System Design方面的想法，将小M还没有能够达成的梦想实现。

Squence	Problem	Level	Language	Video Tutorial
0	2 Sum II - Input array is sorted.java	Medium	Java
1	2 Sum II.java	Medium	Java
2	2 Sum.java	Medium	Java	Link
3	3 Sum Closest.java	Medium	Java
4	3 Sum Smaller.java		Java
5	3 Sum.java	Medium	Java
6	4 Sum.java	Medium	Java
7	A+B.java	Easy	Java
8	Add and Search Word.java	Medium	Java
9	Add Binary.java	Easy	Java
10	Add Two Numbers II.java	Medium	Java
11	Add Two Numbers.java	Easy	Java
12	Alien Dictionary.java	Hard	Java
13	Anagrams.java	Medium	Java
14	Backpack II.java	Medium	Java
15	Backpack.java	Medium	Java
16	Balanced Binary Tree.java	Medium	Java
17	Best Time to Buy and Sell Stock I.java	Medium	Java
18	Best Time to Buy and Sell Stock II.java	Medium	Java
19	Best Time to Buy and Sell Stock III .java	Medium	Java
20	Best Time to Buy and Sell Stock IV.java	Hard	Java
21	Binary Representation.java	Hard	Java
22	Binary Search Tree Iterator.java	Hard	Java
23	Binary Tree Inorder Traversal.java	Easy	Java
24	Binary Tree Level Order Traversal II.java	Medium	Java
25	Binary Tree Level Order Traversal.java	Medium	Java
26	Binary Tree Longest Consecutive Sequence.java	Medium	Java
27	Binary Tree Maximum Path Sum II.java	Medium	Java
28	Binary Tree Maximum Path Sum.java	Medium	Java
29	Binary Tree Path Sum.java	Easy	Java
30	Binary Tree Paths.java	Easy	Java
31	Binary Tree Postorder Traversal.java	Easy	Java
32	Binary Tree Preorder Traversal.java	Easy	Java
33	Binary Tree Right Side View.java	Medium	Java
34	Binary Tree Serialization.java	Medium	Java
35	Binary Tree Zigzag Level Order Traversal.java	Medium	Java
36	Building Outline.java	Hard	Java
37	Burst Balloons.java		Java
38	Change to Anagram.java	Easy	Java
39	Classical Binary Search.java	Easy	Java
40	Climbing Stairs.java	Easy	Java
41	Clone Graph.java	Medium	Java
42	Closest Binary Search Tree Value.java	Easy	Java
43	Closest Number in Sorted Array.java	Easy	Java
44	Coins in a Line.java		Java
45	ColorGrid.java	Medium	Java
46	Combination Sum II.java	Medium	Java
47	Combination Sum.java	Medium	Java
48	Combinations.java	Medium	Java
49	Compare Strings.java	Easy	Java
50	Complete Binary Tree.java	Easy	Java
51	Construct Binary Tree from Inorder and Postorder Traversal.java	Medium	Java
52	Construct Binary Tree from Inorder and Preorder Traversal.java	Medium	Java
53	Container With Most Water.java		Java
54	Convert Binary Search Tree to Doubly Linked List.java	Medium	Java
55	Convert Expression to Polish Notation.java	Hard	Java
56	Convert Expression to Reverse Polish Notation.java	Hard	Java
57	Convert Integer A to Integer B.java	Easy	Java
58	Convert Sorted Array to Binary Search Tree With Minimal Height.java	Easy	Java
59	Convert Sorted List to Binary Search Tree.java	Medium	Java
60	Copy List with Random Pointer.java	Medium	Java
61	Cosine Similarity.java	Easy	Java
62	Count 1 in Binary.java	Easy	Java
63	Count and Say.java	Easy	Java
64	Count of Smaller Number before itself.java	Hard	Java
65	Count of Smaller Number.java	Medium	Java
66	Count Primes.java	Easy	Java
67	Course Schedule II.java	Medium	Java
68	Course Schedule.java	Medium	Java
69	Data Stream Median.java	Hard	Java
70	Delete Digits.java	Medium	Java
71	Delete Node in the Middle of Singly Linked List.java	Easy	Java
72	Distinct Subsequences.java	Hard	Java
73	Edit Distance.java	Medium	Java
74	Encode and Decode Strings.java	Medium	Java
75	ExcelSheetColumnNumber .java	Easy	Java
76	Expression Evaluation.java	Hard	Java
77	Expression Tree Build.java	Hard	Java
78	Fast Power.java	Medium	Java
79	Fibonacci.java	Easy	Java
80	Find Minimum in Rotated Sorted Array II.java		Java
81	Find Minimum in Rotated Sorted Array.java		Java
82	Find Peak Element II.java		Java
83	Find Peak Element.java		Java
84	Find the Connected Component in the Undirected Graph.java	Medium	Java
85	Find the Weak Connected Component in the Directed Graph.java	Medium	Java
86	First Bad Version.java	Medium	Java
87	First Missing Positive.java		Java
88	Flatten 2D Vector.java		Java
89	Flatten Binary Tree to Linked List.java	Easy	Java
90	Flattern 2D Vector.java		Java
91	Flip Game II.java		Java
92	Flip Game.java		Java
93	Fraction to Recurring Decimal.java		Java
94	Game of Life.java		Java
95	Gas Station.java		Java
96	Generate Parentheses.java		Java
97	Graph Valid Tree.java	Medium	Java
98	Gray Code.java	Medium	Java
99	Group Anagrams.java	Medium	Java
100	Group Shifted Strings.java	Easy	Java
101	H-Index II.java		Java
102	H-Index.java		Java
103	Happy Number.java	Easy	Java
104	Hash Function.java	Easy	Java
105	HashHeap.java	Hard	Java
106	HashWithArray.java	Easy	Java
107	HashWithCustomizedClass(LinkedList).java	Medium	Java
108	Heapify.java	Medium	Java
109	House Robber II.java	Medium	Java
110	House Robber III.java	Hard	Java
111	House Robber.java	Easy	Java
112	Identical Binary Tree.java	Easy	Java
113	Implement Queue by Two Stacks.java		Java
114	Implement Stack by Two Queues.java		Java
115	Implement Stack.java		Java
116	Implement strStr().java		Java
117	Implement Trie (Prefix Tree).java		Java
118	Implement Trie.java	Medium	Java
119	IndexMatch.java	Easy	Java
120	Inorder Successor in Binary Search Tree.java	Medium	Java
121	Insert Interval.java	Easy	Java
122	Insert Node in a Binary Search Tree .java	Easy	Java
123	Insertion Sort List.java		Java
124	Integer to English Words.java		Java
125	Interleaving Positive and Negative Numbers.java		Java
126	Interleaving String.java		Java
127	Intersection of Two Linked Lists.java	Easy	Java
128	Interval Minimum Number.java	Medium	Java
129	Interval Sum II.java	Hard	Java
130	Interval Sum.java	Medium	Java
131	Invert Binary Tree.java	Easy	Java
132	Isomorphic Strings.java	Easy	Java
133	Jump Game II.java	Hard	Java
134	Jump Game.java	Medium	Java
135	Kth Largest Element.java	Medium	Java
136	Kth Smallest Element in a BST.java		Java
137	Kth Smallest Number in Sorted Matrix.java	Medium	Java
138	Kth Smallest Sum In Two Sorted Arrays.java	Hard	Java
139	Largest Number.java		Java
140	Largest Rectangle in Histogram.java		Java
141	Last Position of Target.java		Java
142	Length of Last Word.java		Java
143	Letter Combinations of a Phone Number.java	Medium	Java
144	Linked List Cycle II.java		Java
145	Linked List Cycle.java		Java
146	Longest Common Prefix.java	Medium	Java
147	Longest Common Subsequence.java		Java
148	Longest Common Substring.java		Java
149	Longest Consecutive Sequence.java		Java
150	Longest Increasing Continuous subsequence II.java		Java
151	Longest Increasing Continuous subsequence.java		Java
152	Longest Increasing Subsequence.java		Java
153	Longest Palindromic Substring.java	Medium	Java
154	Longest Substring with At Most K Distinct Characters.java	Medium	Java
155	Longest Substring Without Repeating Characters.java	Medium	Java
156	Longest Words.java		Java
157	Lowest Common Ancestor II.java	Easy	Java
158	Lowest Common Ancestor of a Binary Search Tree.java	Medium	Java
159	Lowest Common Ancestor.java	Easy	Java
160	LRU Cache.java	Hard	Java
161	Majority Number II.java	Medium	Java
162	Majority Number III.java	Medium	Java
163	Majority Number.java	Easy	Java
164	Matrix Zigzag Traversal.java	Easy	Java
165	Max Tree.java	Hard	Java
166	Maximal Square.java	Medium	Java
167	Maximum Depth of Binary Tree.java	Easy	Java
168	Maximum Product Subarray.java		Java
169	Maximum Subarray III.java		Java
170	MaximumSubarray.java		Java
171	MaximumSubarrayII.java		Java
172	Median of two Sorted Arrays.java	Hard	Java
173	Median.java		Java
174	Meeting Rooms II.java	Medium	Java
175	Meeting Rooms.java	Easy	Java
176	Merge Intervals.java	Easy	Java
177	Merge k Sorted Arrays.java	Medium	Java
178	Merge k Sorted Lists.java	Medium	Java
179	Merge Sorted Array II.java		Java
180	Merge Sorted Array.java	Easy	Java
181	Merge Two Sorted List.java	Easy	Java
182	Merge Two Sorted Lists.java		Java
183	Middle of Linked List.java		Java
184	Min Stack.java	Easy	Java
185	Minimum Height Trees.java		Java
186	Minimum Path Sum.java		Java
187	Minimum Size Subarray Sum.java	Medium	Java
188	Minimum Subarray.java		Java
189	Minimum Window Substring.java	Hard	Java
190	MinimumDepthOfBinaryTree.java	Easy	Java
191	Missing Ranges.java		Java
192	Multiply Strings.java	Medium	Java
193	Next Permutation.java	Medium	Java
194	Nim Game.java		Java
195	NQueens.java		Java
196	NQueensII.java		Java
197	Nth to Last Node in List.java		Java
198	Number of Airplane in the sky.java	Medium	Java
199	Number of Islands II.java	Hard	Java
200	Number of Islands.java	Medium	Java
201	Number Triangles.java		Java
202	O(1) Check Power of 2.java		Java
203	One Edit Distance.java	Medium	Java
204	Paint Fence.java		Java
205	Palindrome Linked List.java		Java
206	Palindrome Partitioning II.java		Java
207	Palindrome Partitioning.java		Java
208	Palindrome Permutation II.java	Medium	Java
209	Palindrome Permutation.java	Easy	Java
210	Partition Array by Odd and Even.java		Java
211	Partition Array.java		Java
212	Partition List.java		Java
213	Pascal's Triangle II.java	Easy	Java
214	Peeking Iterator.java		Java
215	Perfect Squares.java		Java
216	Permutation Index.java	Easy	Java
217	Permutation Sequence.java	Medium	Java
218	Permutations II.java	Medium	Java
219	Permutations.java	Medium	Java
220	Plus One.java		Java
221	Populating Next Right Pointers in Each Node II.java	Hard	Java
222	Populating Next Right Pointers in Each Node.java	Medium	Java
223	Pow(x,n).java		Java
224	Power of Three.java	Easy	Java
225	Product of Array Exclude Itself.java		Java
226	QuickSort.java	Easy	Java
227	Recover Rotated Sorted Array.java		Java
228	Rehashing.java	Medium	Java
229	Remove Duplicates from Sorted Array.java		Java
230	Remove Duplicates from Sorted List II.java		Java
231	Remove Duplicates from Sorted List.java		Java
232	Remove Duplicates from Unsorted List.java		Java
233	Remove Linked List Elements.java		Java
234	Remove Node in Binary Search Tree.java	Hard	Java
235	Remove Nth Node From End of List.java		Java
236	Reorder List.java		Java
237	Restore IP Addresses.java		Java
238	Reverse Integer.java		Java
239	Reverse Linked List II .java		Java
240	Reverse Linked List.java	Easy	Java
241	Reverse Words in a String II.java	Medium	Java
242	Reverse Words in a String.java	Medium	Java
243	reverseInteger.java		Java
244	Roman to Integer.java	Easy	Java
245	Rotate Image.java	Medium	Java
246	Rotate List.java		Java
247	Rotate String.java		Java
248	Search a 2D Matrix II.java		Java
249	Search a 2D Matrix.java		Java
250	Search for a Range.java		Java
251	Search Insert Position.java		Java
252	Search Range in Binary Search Tree .java	Medium	Java
253	Search Rotated in Sorted Array II.java		Java
254	Search Rotated in Sorted Array.java	Hard	Java
255	Segment Tree Build II.java	Medium	Java
256	Segment Tree Build.java	Medium	Java
257	Segment Tree Modify.java	Medium	Java
258	Segment Tree Query II.java	Medium	Java
259	Segment Tree Query.java	Medium	Java
260	Serilization and Deserialization Of Binary Tree.java		Java
261	Single Number II.java		Java
262	Single Number III.java		Java
263	Single Number.java		Java
264	Singleton.java		Java
265	Sliding Window Maximum.java		Java
266	Sliding Window Median.java		Java
267	Sort Color.java		Java
268	Sort Colors II.java		Java
269	Sort Letters by Case.java		Java
270	Sort List.java		Java
271	Space Replacement.java		Java
272	Sqrt(x).java		Java
273	Stone Game.java		Java
274	String to Integer(atoi).java	Easy	Java
275	Strobogrammatic Number II.java		Java
276	Strobogrammatic Number.java		Java
277	StrStr.java		Java
278	Subarray Sum Closest.java	Medium	Java
279	Subarray Sum.java	Easy	Java
280	Subset.java	Medium	Java
281	Subsets II.java	Medium	Java
282	Subtree.java	Easy	Java
283	Summary Ranges.java		Java
284	Surrounded Regions.java		Java
285	Swap Nodes in Pairs.java		Java
286	Symmetric Binary Tree.java	Easy	Java
287	The Smallest Difference.java		Java
288	Top K Frequent Words.java	Medium	Java
289	Topological Sorting.java	Medium	Java
290	Total Occurrence of Target.java		Java
291	Trailing Zeros.java		Java
292	Trapping Rain Water II.java	Hard	Java
293	Trapping Rain Water.java	Medium	Java
294	Triangle Count.java		Java
295	Tweaked Identical Binary Tree.java	Easy	Java
296	Two Lists Sum.java		Java
297	Two Strings Are Anagrams.java	Easy	Java
298	Ugly Number II.java		Java
299	Ugly Number.java	Medium	Java
300	Unique Binary Search Tree II.java		Java
301	Unique Binary Search Tree.java		Java
302	Unique Characters.java		Java
303	Unique Path.java	Medium	Java
304	Unique Paths II.java		Java
305	Unique Word Abbreviation.java		Java
306	Update Bits.java		Java
307	Valid Anagram.java		Java
308	Valid Palindrome.java	Easy	Java	Link
309	Valid Parentheses.java	Easy	Java
310	Valid Sudoku.java	Easy	Java
311	Validate Binary Search Tree.java	Medium	Java
312	Wiggle Sort.java		Java
313	Wood Cut.java		Java
314	Word Break II.java	Hard	Java
315	Word Break.java	Medium	Java
316	Word Ladder II.java	Hard	Java
317	Word Ladder.java	Medium	Java
318	Word Pattern.java	Easy	Java
319	Word Search II.java	Hard	Java
320	Word Search.java	Medium	Java
321	Zigzag Iterator.java		Java