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LeetCode

My C++ solutions of LeetCode Online Judge questions. So far, 447 out of 581 algorithms questions have been included, the indices are not continuous because I solve questions in order of descending frequency. I'll keep updating for new questions and better solutions. Also, feel free to visit my LeetCode discuss home page for latest posts and discussions.

Table

#	Title	Solution	Difficulty	Tag	Discuss
1	Two Sum	C++	Easy	Array / Hash Table	discuss
2	Add Two Numbers	C++	Medium	Linked List	discuss
3	Longest Substring Without Repeating Characters	C++	Medium	Hash Table / Two Pointers	discuss
4	Median of Two Sorted Arrays	C++	Hard	Array / Binary Search	discuss
5	Longest Palindromic Substring	C++	Medium	String	discuss
6	ZigZag Conversion	C++	Medium	String	discuss
7	Reverse Integer	C++	Easy	Math	discuss
8	String to Integer (atoi)	C++	Medium	String	discuss
9	Palindrome Number	C++	Easy	Math	discuss
10	Regular Expression Matching	C++	Hard	String / Dynamic Programming / Backtracking	discuss
11	Container With Most Water	C++	Medium	Array / Two Pointers	discuss
12	Integer to Roman	C++	Medium	String	discuss
13	Roman to Integer	C++	Easy	String	discuss
14	Longest Common Prefix	C++	Easy	String	discuss
15	3Sum	C++	Medium	Array / Two Pointers	discuss
16	3Sum Closest	C++	Medium	Array / Two Pointers	discuss
17	Letter Combinations of a Phone Number	C++	Medium	Backtracking / String	discuss
18	4Sum	C++	Medium	Array	discuss
19	Remove Nth Node From End of List	C++	Medium	Linked List / Two Pointers	discuss
20	Valid Parentheses	C++	Easy	Stack	discuss
21	Merge Two Sorted Lists	C++	Easy	Linked List	discuss
22	Generate Parentheses	C++	Medium	String / Backtracking	discuss
23	Merge k Sorted Lists	C++	Hard	Linked List / Heap	discuss
24	Swap Nodes in Pairs	C++	Medium	Linked List	discuss
25	Reverse Nodes in k-Group	C++	Hard	Linked List	discuss
26	Remove Duplicates from Sorted Array	C++	Easy	Array / Two Pointers	discuss
27	Remove Element	C++	Easy	Array / Two Pointers	discuss
28	Implement strStr()	C++	Easy	String	discuss
31	Next Permutation	C++	Medium	Array	dsicuss
33	Search in Rotated Sorted Array	C++	Medium	Array / Binary Search	discuss
34	Search for a Range	C++	Medium	Array / Binary Search	discuss
35	Search Insert Position	C++	Easy	Array / Binary Search	discuss
36	Valid Sudoku	C++	Medium	Hash Table	discuss
38	Count and Say	C++	Easy	String	discuss
39	Combination Sum	C++	Medium	Array / Backtracking	discuss
40	Combination Sum II	C++	Medium	Array / Backtracking	discuss
41	First Missing Positive	C++	Hard	Array	discuss
42	Trapping Rain Water	C++	Hard	Array / Two Pointers / Stack	discuss
43	Multiply Strings	C++	Medium	String	discuss
44	Wildcard Matching	C++	Hard	String / Backtracking / Greedy	discuss
45	Jump Game II	C++	Hard	Array / Greedy	discuss
46	Permutations	C++	Medium	Backtracking	discuss
47	Permutations II	C++	Medium	Backtracking	discuss
48	Rotate Image	C++	Medium	Matrix	discuss
49	Group Anagrams	C++	Medium	Hash Table / String	discuss
50	Pow(x, n)	C++	Medium	Binary Search	discuss
53	Maximum Subarray	C++	Easy	Dynamic Programming / Array	discuss
54	Spiral Matrix	C++	Medium	Array	discuss
55	Jump Game	C++	Medium	Array / Greedy	discuss
56	Merge Intervals	C++	Medium	Array / Sort	discuss
57	Insert Interval	C++	Hard	Array / Sort	discuss
58	Length of Last Word	C++	Easy	String	discuss
59	Spiral Matrix II	C++	Medium	Array	discuss
60	Permutation Sequence	C++	Medium	Backtracking / Math	discuss
61	Rotate List	C++	Medium	Linked List / Two Pointers	discuss
62	Unique Paths	C++	Medium	Array / Dynamic Programming	discuss
63	Unique Paths II	C++	Medium	Array / Dynamic Programming	discuss
64	Minimum Path Sum	C++	Medium	Array / Dynamic Programming	discuss
66	Plus One	C++	Easy	Array / Math	discuss
67	Add Binary	C++	Easy	String	discuss
68	Text Justification	C++	Hard	String	discuss
69	Sqrt(x)	C++	Easy	Binary Search / Math	discuss
70	Climbing Stairs	C++	Easy	Dynamic Programming	discuss
71	Simplify Path	C++	Medium	Stack / String	discuss
73	Set Matrix Zeroes	C++	Medium	Array	discuss
74	Search a 2D Matrix	C++	Medium	Array / Binary Search	discuss
75	Sort Colors	C++	Medium	Array / Two Pointers	discuss
76	Minimum Window Substring	C++	Hard	Hash Table / Two pointers / String	discuss
78	Subsets	C++	Medium	Array / Backtracking	discuss
79	Word Search	C++	Medium	Matrix / Backtracking	discuss
80	Remove Duplicates from Sorted Array II	C++	Medium	Array / Two Pointers	discuss
82	Remove Duplicates from Sorted List II	C++	Medium	Linked List	discuss
83	Remove Duplicates from Sorted List	C++	Easy	Linked List	discuss
85	Maximal Rectangle	C++	Hard	Array	discuss
86	Partition List	C++	Medium	Linked List	discuss
88	Merge Sorted Array	C++	Easy	Array / Two Pointers	discuss
90	Subsets II	C++	Medium	Array / Backtracking	discuss
91	Decode Ways	C++	Medium	Dynamic Programming / String	discuss
92	Reverse Linked List II	C++	Medium	Linked List	discuss
94	Binary Tree Inorder Traversal	C++	Medium	Tree / Stack	discuss
95	Unique Binary Search Trees II	C++	Medium	Tree	discuss
98	Validate Binary Search Tree	C++	Medium	Tree	discuss
99	Recover Binary Search Tree	C++	Hard	Tree / DFS	discuss
100	Same Tree	C++	Easy	Tree / DFS	discuss
101	Symmetric Tree	C++	Easy	Tree	discuss
102	Binary Tree Level Order Traversal	C++	Medium	Tree / DFS / BFS	discuss
103	Binary Tree Zigzag Level Order Traversal	C++	Medium	Tree / BFS	discuss
104	Maximum Depth of Binary Tree	C++	Easy	Tree	discuss
105	Construct Binary Tree from Preorder and Inorder Traversal	C++	Medium	Array / Tree / DFS	discuss
107	Binary Tree Level Order Traversal II	C++	Easy	Tree	discuss
108	Convert Sorted Array to Binary Search Tree	C++	Easy	Tree / DFS	discuss
109	Convert Sorted List to Binary Search Tree	C++	Medium	Linked List / DFS	discuss
110	Balanced Binary Tree	C++	Easy	Tree / DFS	discuss
111	Minimum Depth of Binary Tree	C++	Easy	Tree	discuss
112	Path Sum	C++	Easy	Tree / DFS	discuss
113	Path Sum II	C++	Medium	Tree / DFS	discuss
114	Flatten Binary Tree to Linked List	C++	Medium	Tree / DFS	discuss
116	Populating Next Right Pointers in Each Node	C++	Medium	Tree / BFS	discuss
117	Populating Next Right Pointers in Each Node II	C++	Medium	Tree / Level-order Traversal	discuss
118	Pascal's Triangle	C++	Easy	Array	discuss
119	Pascal's Triangle II	C++	Easy	Array	discuss
120	Triangle	C++	Medium	Array / Dynamic Programming	discuss
121	Best Time to Buy and Sell Stock	C++	Easy	Array / Dynamic Programming	discuss
124	Binary Tree Maximum Path Sum	C++	Hard	Tree / DFS	discuss
125	Valid Palindrome	C++	Easy	String / Two Pointers	discuss
127	Word Ladder	C++	Medium	String / BFS	discuss
128	Longest Consecutive Sequence	C++	Hard	Array / Unoin Find	discuss
129	Sum Root to Leaf Numbers	C++	Medium	Tree / DFS / BFS	discuss
130	Surrounded Regions	C++	Medium	DFS / BFS / Union Find	discuss
131	Palindrome Partitioning	C++	Medium	Backtracking	discuss
133	Clone Graph	C++	Medium	Graph / DFS / BFS	discuss
134	Gas Station	C++	Medium	Greedy	discuss
136	Single Number	C++	Easy	Bit Manipulation	discuss
138	Copy List with Random Pointer	C++	Medium	Hash Table / Linked List	discuss
139	Word Break	C++	Medium	Dynamic Programming	discuss
141	Linked List Cycle	C++	Easy	Linked List / Two Pointers	discuss
142	Linked List Cycle II	C++	Medium	Linked List / Two Pointers	discuss
143	Reorder List	C++	Medium	Linked List	discuss
144	Binary Tree Preorder Traversal	C++	Medium	Tree / Stack	discuss
145	Binary Tree Postorder Traversal	C++	Hard	Tree / Stack	discuss
146	LRU Cache	C++	Hard	Design	discuss
151	Reverse Words in a String	C++	Medium	String	discuss
155	Min Stack	C++	Easy	Stack / Design	discuss
157	Read N Characters Given Read4	C++	Easy	String	discuss
158	Read N Characters Given Read4 II - Call multiple times	C++	Hard	String	discuss
159	Longest Substring with At Most Two Distinct Characters	C++	Hard	String / Two Pointers	discuss
161	One Edit Distance	C++	Medium	String	discuss
162	Find Peak Element	C++	Medium	Binary Search	discuss
163	Missing Ranges	C++	Medium	Array	discuss
168	Excel Sheet Column Title	C++	Easy	Math	discuss
169	Majority Element	C++	Easy	Array	discuss
171	Excel Sheet Column Number	C++	Easy	Math	discuss
173	Binary Search Tree Iterator	C++	Medium	Tree / Stack / Design	discuss
186	Reverse Words in a String II	C++	Medium	String	discuss
191	Number of 1 Bits	C++	Easy	Bit Manipulation	discuss
198	House Robber	C++	Easy	Dynamic Programming	discuss
200	Number of Islands	C++	Medium	BFS / Union Find	discuss
205	Isomorphic Strings	C++	Easy	Hash Table	discuss
206	Reverse Linked List	C++	Easy	Linked List	discuss
207	Course Schedule	C++	Medium	Graph / BFS / Topological Sort	discuss
208	Implement Trie (Prefix Tree)	C++	Medium	Trie / Design	discuss
209	Minimum Size Subarray Sum	C++	Medium	Array / Two Pointers	discuss
210	Course Schedule II	C++	Medium	Graph / BFS / Topological Sort	discuss
211	Add and Search Word - Data structure design	C++	Medium	Design / Trie	discuss
212	Word Search II	C++	Hard	Backtracking / Trie	discuss
214	Shortest Palindrome	C++	Hard	String	discuss
215	Kth Largest Element in an Array	C++	Medium	Sort / Partition	discuss
221	Maximal Square	C++	Medium	Dynamic Programming / BFS	discuss
223	Rectangle Area	C++	Medium	Math	discuss
224	Basic Calculator	C++	Hard	String / Stack	discuss
226	Invert Binary Tree	C++	Easy	Tree	discuss
227	Basic Calculator II	C++	Medium	String	discuss
228	Summary Ranges	C++	Medium	Array	discuss
229	Majority Element II	C++	Medium	Array	discuss
230	Kth Smallest Element in a BST	C++	Medium	Tree	discuss
231	Power of Two	C++	Easy	Bit Manipulation	discuss
234	Palindrome Linked List	C++	Easy	Linked List / Two Pointers	discuss
235	Lowest Common Ancestor of a Binary Search Tree	C++	Easy	Tree	discuss
236	Lowest Common Ancestor of a Binary Tree	C++	Medium	Tree	discuss
238	Product of Array Except Self	C++	Medium	Array	discuss
239	Sliding Window Maximum	C++	Hard	Heap	discuss
240	Search a 2D Matrix II	C++	Medium	Binary Search / Divide and Conquer	discuss
244	Shortest Word Distance II	C++	Medium	Hash Table / Design	discuss
246	Strobogrammatic Number	C++	Easy	Hash Table / Math	discuss
247	Strobogrammatic Number II	C++	Medium	Math / Recursion	discuss
249	Group Shifted Strings	C++	Medium	String	discuss
251	Flatten 2D Vector	C++	Medium	Design	discuss
252	Meeting Rooms	C++	Easy	Sort	discuss
253	Meeting Rooms II	C++	Medium	Heap / Sort	discuss
255	Verify Preorder Sequence in Binary Search Tree	C++	Medium	Stack / Tree	discuss
257	Binary Tree Paths	C++	Easy	Tree / DFS / BFS	discuss
258	Add Digits	C++	Easy	Math	discuss
259	3Sum Smaller	C++	Medium	Array / Two Pointers	discuss
261	Graph Valid Tree	C++	Medium	Graph / BFS / DFS / Union Find	discuss
263	Ugly Number	C++	Easy	Math	discuss
264	Ugly Number II	C++	Medium	Dynamic Programming / Math	discuss
266	Palindrome Permutation	C++	Easy	Hash Table	discuss
267	Palindrome Permutation II	C++	Medium	Backtracking	discuss
268	Missing Number	C++	Easy	Array / Bit Manipulation	discuss
269	Alien Dictionary	C++	Hard	Graph / Topological Sort	discuss
270	Closest Binary Search Tree Value	C++	Easy	Tree / Binary Search	discuss
271	Encode and Decode Strings	C++	Medium	String / Design	discuss
272	Closest Binary Search Tree Value II	C++	Hard	Tree / Stack	discuss
273	Integer to English Words	C++	Hard	String	discuss
274	H-Index	C++	Medium	Sort	discuss
275	H-Index II	C++	Medium	Binary Search	discuss
276	Paint Fence	C++	Easy	Dynamic Programming	discuss
277	Find the Celebrity	C++	Medium	Array	discuss
278	First Bad Version	C++	Easy	Binary Search	discuss
279	Perfect Squares	C++	Medium	Math / Dynamic Programming	discuss
280	Wiggle Sort	C++	Easy	Array	discuss
281	Zigzag Iterator	C++	Medium	Design	discuss
282	Expression Add Operators	C++	Hard	Divide and Conquer	discuss
283	Move Zeroes	C++	Easy	Array / Two Pointers	discuss
284	Peeking Iterator	C++	Medum	Design	discuss
285	Inorder Successor in BST	C++	Medium	Tree	discuss
286	Walls and Gates	C++	Medium	BFS	discuss
289	Game of Life	C++	Medium	Array	discuss
290	Word Pattern	C++	Easy	Hash Table	discuss
293	Flip Game	C++	Easy	String	discuss
294	Flip Game II	C++	Medium	Backtracking	discuss
295	Find Median from Data Stream	C++	Hard	Heap / Design	discuss
297	Serialize and Deserialize Binary Tree	C++	Hard	Tree / Design	discuss
298	Binary Tree Longest Consecutive Sequence	C++	Medium	Tree	discuss
300	Longest Increasing Subsequence	C++	Medium	Binary Search / Dynamic Programming	discuss
301	Remove Invalid Parentheses	C++	Hard	Backtracking / DFS / BFS	discuss
303	Range Sum Query - Immutable	C++	Easy	Dynamic Programming	discuss
304	Range Sum Query 2D - Immutable	C++	Medium	Dynamic Programming	discuss
305	Number of Islands II	C++	Hard	Union Find	discuss
307	Range Sum Query - Mutable	C++	Medium	Segment Tree	discuss
309	Best Time to Buy and Sell Stock with Cooldown	C++	Medium	Dynamic Programming	discuss
310	Minimum Height Trees	C++	Medium	BFS/ Graph	discuss
311	Sparse Matrix Multiplication	C++	Medium	Matrix	discuss
313	Super Ugly Number	C++	Medium	Dynamic Programming / Math	discuss
314	Binary Tree Vertical Order Traversal	C++	Medium	BFS	discuss
315	Count of Smaller Numbers After Self	C++	Hard	Divide and Conqur / Binary Search Tree	discuss
317	Shortest Distance from All Buildings	C++	Hard	BFS	discuss
318	Maximum Product of Word Lengths	C++	Medium	Bit Manipulation	discuss
323	Number of Connected Components in an Undirected Graph	C++	Medium	Graph / Union Find / BFS / DFS	discuss
325	Maximum Size Subarray Sum Equals k	C++	Medium	Array / Hash Table	discuss
329	Longest Increasing Path in a Matrix	C++	Hard	DFS / Memorization	discuss
331	Verify Preorder Serialization of a Binary Tree	C++	Medium	Stack	discuss
332	Reconstruct Itinerary	C++	Medium	Graph / DFS	discuss
333	Largest BST Subtree	C++	Medium	Tree	discuss
334	Increasing Triplet Subsequence	C++	Medium	Array	discuss
336	Palindrome Pairs	C++	Hard	Hash Table / String / Trie	discuss
339	Nested List Weight Sum	C++	Easy	DFS	discuss
340	Longest Substring with At Most K Distinct Characters	C++	Hard	Hash Table / String	discuss
341	Flatten Nested List Iterator	C++	Medium	Stack / Design	discuss
344	Reverse String	C++	Easy	String	discuss
347	Top K Frequent Elements	C++	Medium	Hash Table / Heap	discuss
348	Design Tic-Tac-Toe	C++	Medium	Design	discuss
351	Android Unlock Patterns	C++	Medium	DFS / Dynamic Programming	discuss
354	Russian Doll Envelopes	C++	Hard	Binary Search / Dynamic Programming	discuss
355	Design Twitter	C++	Medium	Hash Table / Design	discuss
359	Logger Rate Limiter	C++	Easy	Hash Table / Design
360	Sort Transformed Array	C++	Medium	Math / Two Pointers	discuss
361	Bomb Enemy	C++	Medium	Dynamic Programming	discuss
362	Design Hit Counter	C++	Medium	Design	discuss
364	Nested List Weight Sum II	C++	Medium	DFS	discuss
369	Plus One Linked List	C++	Medium	Linked List	discuss
373	Find K Pairs with Smallest Sums	C++	Medium	Heap	discuss
377	Combination Sum IV	C++	Medium	Dynamic Programming	discuss
378	Kth Smallest Element in a Sorted Matrix	C++	Medium	Binary Search / Heap	discuss
380	Insert Delete GetRandom O(1)	C++	Medium	Hash Table / Design	discuss
382	Linked List Random Node	C++	Medium	Reservoir Sampling	discuss
394	Decode String	C++	Medium	String / DFS	discuss
398	Random Pick Index	C++	Medium	Reservoir Sampling	discuss
399	Evaluate Division	C++	Medium	Graph	discuss
402	Remove K Digits	C++	Medium	Greedy	discuss
404	Sum of Left Leaves	C++	Easy	Tree	discuss
408	Valid Word Abbreviation	C++	Easy	String	discuss
409	Longest Palindrome	C++	Easy	Hash Table	discuss
411	Minimum Unique Word Abbreviation	C++	Hard	Backtracking	discuss
412	Fizz Buzz	C++	Easy	Array	discuss
416	Partition Equal Subset Sum	C++	Medium	Dynamic Programming	discuss
417	Pacific Atlantic Water Flow	C++	Medium	DFS / BFS	discuss
418	Sentence Screen Fitting	C++	Medium	Dynamic Programming
433	Minimum Genetic Mutation	C++	Medium	BFS	discuss
435	Non-overlapping Intervals	C++	Medium	Greedy	discuss
436	Find Right Interval	C++	Medium	Array / Binary Search	discuss
438	Find All Anagrams in a String	C++	Easy	Hash Table	discuss
441	Arranging Coins	C++	Easy	Math	discuss
444	Sequence Reconstruction	C++	Medium	Graph / Topological Sort	discuss
450	Delete Node in a BST	C++	Medium	Tree	discuss
451	Sort Characters By Frequency	C++	Medium	Hash Table / Heap	discuss
461	Hamming Distance	C++	Easy	Bit Manipulation	discuss
467	Unique Substrings in Wraparound String	C++	Medium	Dynamic Programming	discuss
473	Matchsticks to Square	C++	Medium	DFS	discuss
477	Total Hamming Distance	C++	Medium	Bit Manipulation	discuss
482	License Key Formatting	C++	Medium	Array	discuss
484	Find Permutation	C++	Medium	Greedy	discuss
486	Predict the Winner	C++	Medium	Dynamic Programming / Minimax	discuss
487	Max Consecutive Ones II	C++	Medium	Two Pointers	discuss
489	Robot Room Cleaner	C++	Hard	DFS	discuss
490	The Maze	C++	Medium	BFS / DFS
494	Target Sum	C++	Medium	Backtracking	discuss
496	Next Greater Element I	C++	Easy	Stack	discuss
498	Diagonal Traverse	C++	Medium	Matrix	discuss
499	The Maze III	C++	Hard	DFS / BFS
503	Next Greater Element II	C++	Medium	Stack	discuss
505	The Maze II	C++	Medium	DFS / BFS	discuss
508	Most Frequent Subtree Sum	C++	Medium	Tree / Hash Table	discuss
513	Find Bottom Left Tree Value	C++	Medium	Tree / BFS / DFS	discuss
515	Find Largest Value in Each Tree Row	C++	Medium	Tree / BFS / DFS	discuss
523	Continuous Subarray Sum	C++	Medium	Dynamic Programming	discuss
524	Longest Word in Dictionary through Deleting	C++	Medium	Two Pointers	discuss
525	Contiguous Array	C++	Medium	Hash Table	discuss
531	Lonely Pixel I	C++	Medium	Array / DFS	discuss
535	Encode and Decode TinyURL	C++	Medium	String	discuss
536	Construct Binary Tree from String	C++	Medium	String / Tree	discuss
538	Convert BST to Greater Tree	C++	Easy	DFS	discuss
540	Single Element in a Sorted Array	C++	Medium	Array / Binary Search	discuss
541	Reverse String II	C++	Easy	String	discuss
542	01 Matrix	C++	Medium	BFS / DFS	discuss
543	Diameter of Binary Tree	C++	Easy	Tree	discuss
547	Friend Circles	C++	Medium	DFS / Union Find	discuss
549	Binary Tree Longest Consecutive Sequence II	C++	Medium	Tree	discuss
554	Brick Wall	C++	Medium	Hash Table	discuss
556	Next Greater Element III	C++	Medium	String
560	Subarray Sum Equals K	C++	Medium	Array / Map	discuss
562	Longest Line of Consecutive One in Matrix	C++	Medium	Array	discuss
565	Array Nesting	C++	Medium	Array	discuss
566	Reshape the Matrix	C++	Easy	Array	discuss
567	Permutation in String	C++	Medium	Two Pointers	discuss
572	Subtree of Another Tree	C++	Easy	Tree	discuss
582	Kill Process	C++	Medium	Tree / BFS / DFS	discuss
583	Delete Operation for Two Strings	C++	Medium	Dynamic Programming	discuss
599	Minimum Index Sum of Two Lists	C++	Easy	Hash Table	discuss
606	Construct String from Binary Tree	C++	Easy	Tree / String	discuss
611	Valid Triangle Number	C++	Medium	Array	discuss
616	Add Bold Tag in String	C++	Medium	String	disucss
621	Task Scheduler	C++	Medium	Array / Queue	discuss
632	Smallest Range	C++	Hard	Two Pointers	discuss
633	Sum of Square Numbers	C++	Easy	Math	discuss
635	Design Log Storage System	C++	Medium	String / Design	discuss
636	Exclusive Time of Functions	C++	Medium	Stack	discuss
637	Average of Levels in Binary Tree	C++	Easy	BFS	discuss
639	Decode Ways II	C++	Hard	Dynamic Programming	discuss
642	Design Search Autocomplete System	C++	Hard	Design / Trie	discuss
643	Maximum Average Subarray I	C++	Easy	Array	discuss
645	Set Mismatch	C++	Easy	Hash Table / Math	discuss
647	Palindromic Substrings	C++	Medium	String	discuss
648	Replace Words	C++	Medium	Hash Table / Trie	discuss
652	Find Duplicate Subtrees	C++	Medium	Tree	discuss
653	Two Sum IV - Input is a BST	C++	Easy	DFS	discuss
654	Maximum Binary Tree	C++	Medium	Tree	discuss
657	Judge Route Circle	C++	Easy	String	discuss
658	Find K Closest Elements	C++	Medium	Binary Search	discuss
659	Split Array into Consecutive Subsequences	C++	Medium	Greedy	discuss
662	Maximum Width of Binary Tree	C++	Medium	Tree / BFS / DFS	discuss
663	Equal Tree Partition	C++	Medium	Tree	discuss
665	Non-decreasing Array	C++	Easy	Array	discuss
669	Trim a Binary Search Tree	C++	Easy	Tree	discuss
670	Maximum Swap	C++	Medium	Array / Math	discuss
671	Second Minimum Node In a Binary Tree	C++	Easy	Tree	discuss
673	Number of Longest Increasing Subsequence	C++	Medium	Dynamic Programming	discuss
674	Longest Continuous Increasing Subsequence	C++	Easy	Array	discuss
676	Implement Magic Dictionary	C++	Medium	Hash Table / Trie	discuss
677	Map Sum Pairs	C++	Medium	Trie	discuss
679	24 Game	C++	Hard	DFS	discuss
680	Valid Palindrome II	C++	Easy	String	discuss
681	Next Closest Time	C++	Medium	String	discuss
683	K Empty Slots	C++	Hard	Array / Binary Search	discuss
684	Redundant Connection	C++	Medium	Graph / Union Find	discuss
685	Redundant Connection II	C++	Hard	Graph / DFS / Union Find	discuss
686	Repeated String Match	C++	Easy	String	discuss
687	Longest Univalue Path	C++	Easy	Tree / DFS	discuss
688	Knight Probability in Chessboard	C++	Medium	Dynamic Programming	discuss
689	Maximum Sum of 3 Non-Overlapping Subarrays	C++	Hard	Array / Dynamic Programming	discuss
690	Employee Importance	C++	Easy	Hash Table / BFS / DFS	discuss
692	Top K Frequent Words	C++	Medium	Hash Table / Heap	discuss
693	Binary Number with Alternating Bits	C++	Easy	Bit Manipulation	discuss
694	Number of Distinct Islands	C++	Medium	Hash Table / DFS	discuss
695	Max Area of Island	C++	Easy	Array / DFS	discuss
696	Count Binary Substrings	C++	Easy	String	discuss
697	Degree of an Array	C++	Easy	Array	discuss
701	Insert into a Binary Search Tree	C++	Medium	Array
713	Subarray Product Less Than K	C++	Medium	Array	discuss
717	1-bit and 2-bit Characters	C++	Easy	Array	discuss
718	Maximum Length of Repeated Subarray	C++	Medium	Array / Dynamic Programming	discuss
720	Longest Word in Dictionary	C++	Easy	Hash Table / Trie	discuss
723	Candy Crush	C++	Medium	Array / Two Pointers	discuss
724	Find Pivot Index	C++	Easy	Array	discuss
725	Split Linked List in Parts	C++	Medium	Linked List	discuss
728	Self Dividing Numbers	C++	Easy	Math	discuss
729	My Calendar I	C++	Medium	Array	discuss
733	Flood Fill	C++	Easy	DFS	discuss
734	Sentence Similarity	C++	Easy	Hash Table	discuss
735	Asteroid Collision	C++	Medium	Stack	discuss
739	Daily Temperatures	C++	Medium	Stack / Hash Table	discuss
740	Delete and Earn	C++	Medium	Dynamic Programming	discuss
742	Closest Leaf in a Binary Tree	C++	Medium	Tree / Graph	discuss
746	Min Cost Climbing Stairs	C++	Easy	Array / Dynamic Programming	discuss
747	Largest Number At Least Twice of Others	C++	Easy	Array	discuss
750	Number Of Corner Rectangles	C++	Medium	Dynamic Programming
753	Cracking the Safe	C++	Hard	DFS
758	Bold Words in String	C++	Easy	String	discuss
760	Find Anagram Mappings	C++	Easy	Hash Table	discuss
763	Partition Labels	C++	Medium	Two Pointers / Greedy	disucss
765	Couples Holding Hands	C++	Hard	Greedy / Union Find / Greedy	disucss
766	Toeplitz Matrix	C++	Easy	Array	discuss
769	Max Chunks To Make Sorted	C++	Medium	Array	discuss
771	Jewels and Stones	C++	Easy	Hash Table	discuss
773	Sliding Puzzle	C++	Hard	BFS
777	Swap Adjacent in LR String	C++	Medium	Brainteaser	discuss
779	K-th Symbol in Grammar	C++	Medium	Recursion	discuss
783	Minimum Distance Between BST Nodes	C++	Easy	Tree	discuss
784	Letter Case Permutation	C++	Easy	String	discuss
785	Is Graph Bipartite	C++	Medium	Graph	discuss
787	Cheapest Flights Within K Stops	C++	Medium	Graph / Heap	discuss
791	Custom Sort String	C++	Medium	String	discuss
792	Number of Matching Subsequences	C++	Medium	Array	discuss
797	All Paths From Source to Target	C++	Medium	DFS / Graph	discuss
798	Smallest Rotation with Highest Score	C++	Hard	Array	discuss
799	Champagne Tower	C++	Medium	Array	discuss
802	Find Eventual Safe States	C++	Medium	DFS / Graph	discuss
803	Bricks Falling When Hit	C++	Hard	Union Find	discuss
804	Unique Morse Code Words	C++	Easy	String	discuss
805	Split Array With Same Average	C++	Hard	Math
806	Number of Lines To Write String	C++	Easy	String	discuss
807	Max Increase to Keep City Skyline	C++	Medium	Array	discuss
809	Expressive Words	C++	Medium	String	discuss
814	Binary Tree Pruning	C++	Medium	Tree	discuss
815	Bus Routes	C++	Hard	BFS	discuss
819	Most Common Word	C++	Easy	String	discuss
820	Short Encoding of Words	C++	Medium	Trie	discuss
821	Shortest Distance to a Character	C++	Easy	String	discuss
826	Most Profit Assigning Work	C++	Medium	Two Pointers / Binary Search	discuss
830	Positions of Large Groups	C++	Easy	Array	discuss
832	Flipping an Image	C++	Easy	Array	discuss
834	Sum of Distances in Tree	C++	Hard	Tree / DFS	discuss
836	Rectangle Overlap	C++	Easy	Math	discuss
841	Keys and Rooms	C++	Medium	DFS / BFS / Graph	discuss
843	Guess the Word	C++	Hard	Minimax
844	Backspace String Compare	C++	Easy	Stack / Two Pointers	discuss
845	Longest Mountain in Array	C++	Medium	Two Pointers	discuss
846	Hand of Straights	C++	Medium	Map	discuss
848	Shifting Letters	C++	Medium	String	disucss
849	Maximize Distance to Closest Person	C++	Easy	Array	discuss
852	Peak Index in a Mountain Array	C++	Easy	Binary Search	disucss
853	Car Fleet	C++	Medium	Stack
855	Exam Room	C++	Medium	Map	discuss
857	Minimum Cost to Hire K Workers	C++	Hard	Heap
859	Buddy Strings	C++	Easy	String	discuss
872	Leaf-Similar Trees	C++	Easy	Tree / DFS	discuss
876	Middle of the Linked List	C++	Easy	Linked List	disucss
884	Uncommon Words from Two Sentences	C++	Easy	Hash Table	discuss
888	Fair Candy Swap	C++	Easy	Array	discuss
889	Construct Binary Tree from Preorder and Postorder Traversal	C++	Medium	Tree
890	Find and Replace Pattern	C++	Medium	String	discuss
894	All Possible Full Binary Trees	C++	Medium	Tree / Recursion
896	Monotonic Array	C++	Easy	Array	discuss
900	RLE Iterator	C++	Medium	Array
904	Fruit Into Baskets	C++	Medium	Two Pointers
911	Online Election	C++	Medium	Binary Search / Map
914	X of a Kind in a Deck of Cards	C++	Easy	Array / Math
916	Word Subsets	C++	Medium	String
925	Long Pressed Name	C++	Easy	String	discuss
929	Unique Email Addresses	C++	Easy	String
932	Beautiful Array	C++	Medium	Divide and Conquer
933	Number of Recent Calls	C++	Easy	Queue
935	Knight Dialer	C++	Medium	Dynamic Programming	discuss
938	Range Sum of BST	C++	Medium	Tree	discuss
939	Minimum Area Rectangle	C++	Medium	Hash Table	discuss
941	Valid Mountain Array	C++	Easy	Array
946	Validate Stack Sequences	C++	Medium	Stack
951	Flip Equivalent Binary Trees	C++	Medium	Tree	discuss