My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
每个题目都保证击败超过80%的提交，并尽量给出多种解法并分析算法复杂度。
每日持续更新中，欢迎交流，欢迎star :D

另外，

• algorithm文件夹对经典算法作了简单介绍并给出代码模板，方便刷题参考使用；
• CodingInterview给出了《剑指offer》第2版中对应的LeetCode题目。

#	题目	题解	难度
1	Two Sum	C++	Easy
2	Add Two Numbers	C++	Medium
3	Longest Substring Without Repeating Characters	C++	Medium
4	Median of Two Sorted Arrays	C++	Hard
5	Longest Palindromic Substring	C++	Medium
6	ZigZag Conversion	C++	Medium
7	Reverse Integer	C++	Easy
8	String to Integer (atoi)	C++	Medium
9	Palindrome Number	C++	Easy
10	Regular Expression Matching	C++	Hard
11	Container With Most Water	C++	Medium
12	Integer to Roman	C++	Medium
13	Roman to Integer	C++	Easy
14	Longest Common Prefix	C++	Easy
15	3Sum	C++	Medium
16	3Sum Closest	C++	Medium
17	Letter Combinations of a Phone Number	C++	Medium
18	4Sum	C++	Medium
19	Remove Nth Node From End of List	C++	Medium
20	Valid Parentheses	C++	Easy
21	Merge Two Sorted Lists	C++	Easy
22	Generate Parentheses	C++	Medium
23	Merge k Sorted Lists	C++	Hard
24	Swap Nodes in Pairs	C++	Medium
26	Remove Duplicates from Sorted Array	C++	Easy
27	Remove Element	C++	Easy
28	Implement strStr()	C++	Easy
29	Divide Two Integers	C++	Medium
31	Next Permutation	C++	Medium
32	Longest Valid Parentheses	C++	Hard
33	Search in Rotated Sorted Array	C++	Medium
34	Find First and Last Position of Element in Sorted	C++	Medium
35	Search Insert Position	C++	Easy
36	Valid Sudoku	C++	Medium
38	Count and Say	C++	Easy
39	Combination Sum	C++	Medium
40	Combination Sum II	C++	Medium
41	First Missing Positive	C++	Hard
42	Trapping Rain Water	C++	Hard
43	Multiply Strings	C++	Medium
44	Wildcard Matching	C++	Hard
45	Jump Game II	C++	Hard
46	Permutations	C++	Medium
47	Permutations II	C++	Medium
48	Rotate Image	C++	Medium
49	Group Anagrams	C++	Medium
50	Pow(x, n)	C++	Medium
53	Maximum Subarray	C++	Easy
54	Spiral Matrix	C++	Medium
55	Jump Game	C++	Medium
56	Merge Intervals	C++	Medium
58	Length of Last Word	C++	Easy
59	Spiral Matrix II	C++	Medium
60	Permutation Sequence	C++	Medium
61	Rotate List	C++	Medium
62	Unique Paths	C++	Medium
63	Unique Paths II	C++	Medium
64	Minimum Path Sum	C++	Medium
65	Valid Number	C++	Hard
66	Plus One	C++	Easy
67	Add Binary	C++	Easy
69	Sqrt(x)	C++	Easy
70	Climbing Stairs	C++	Easy
71	Simplify Path	C++	Medium
72	Edit Distance	C++	Hard
73	Set Matrix Zeroes	C++	Medium
74	Search a 2D Matrix	C++	Medium
75	Sort Colors	C++	Medium
76	Minimum Window Substring	C++	Hard
77	Combinations	C++	Medium
78	Subsets	C++	Medium
79	Word Search	C++	Medium
80	Remove Duplicates from Sorted Array II	C++	Medium
81	Search in Rotated Sorted Array II	C++	Medium
82	Remove Duplicates from Sorted List II	C++	Medium
83	Remove Duplicates from Sorted List	C++	Easy
84	Largest Rectangle in Histogram	C++	Hard
85	Maximal Rectangle	C++	Hard
86	Partition List	C++	Medium
88	Merge Sorted Array	C++	Easy
89	Gray Code	C++	Medium
90	Subsets II	C++	Medium
91	Decode Ways	C++	Medium
92	Reverse Linked List II	C++	Medium
93	Restore IP Addresses	C++	Medium
94	Binary Tree Inorder Traversal	C++	Medium
95	Unique Binary Search Trees II	C++	Medium
96	Unique Binary Search Trees	C++	Medium
97	Interleaving String	C++	Medium
98	Validate Binary Search Tree	C++	Medium
99	Recover Binary Search Tree	C++	Medium
100	Same Tree	C++	Easy
101	Symmetric Tree	C++	Easy
102	Binary Tree Level Order Traversal	C++	Medium
103	Binary Tree Zigzag Level Order Traversal	C++	Medium
104	Maximum Depth of Binary Tree	C++	Easy
105	Construct Binary Tree from Preorder and Inorder Traversal	C++	Medium
106	Construct Binary Tree from Inorder and Postorder Traversal	C++	Medium
107	Binary Tree Level Order Traversal II	C++	Easy
108	Convert Sorted Array to Binary Search Tree	C++	Easy
109	Convert Sorted List to Binary Search Tree	C++	Medium
110	Balanced Binary Tree	C++	Easy
111	Minimum Depth of Binary Tree	C++	Easy
112	Path Sum	C++	Easy
113	Path Sum II	C++	Medium
114	Flatten Binary Tree to Linked List	C++	Medium
116	Populating Next Right Pointers in Each Node	C++	Medium
117	Populating Next Right Pointers in Each Node II	C++	Medium
118	Pascal's Triangle	C++	Easy
119	Pascal's Triangle II	C++	Easy
120	Triangle	C++	Medium
121	Best Time to Buy and Sell Stock	C++	Easy
122	Best Time to Buy and Sell Stock II	C++	Easy
123	Best Time to Buy and Sell Stock III	C++	Hard
124	Binary Tree Maximum Path Sum	C++	Hard
125	Valid Palindrome	C++	Easy
127	Word Ladder	C++	Medium
128	Longest Consecutive Sequence	C++	Hard
129	Sum Root to Leaf Numbers	C++	Medium
130	Surrounded Regions	C++	Medium
131	Palindrome Partitioning	C++	Medium
133	Clone Graph	C++	Medium
134	Gas Station	C++	Medium
136	Single Number	C++	Easy
137	Single Number II	C++	Medium
138	Copy List with Random Pointer	C++	Medium
139	Word Break	C++	Medium
140	Word Break II	C++	Hard
141	Linked List Cycle	C++	Easy
142	Linked List Cycle II	C++	Medium
143	Reorder List	C++	Medium
144	Binary Tree Preorder Traversal	C++	Medium
145	Binary Tree Postorder Traversal	C++	Hard
146	LRU Cache	C++	Medium
148	Sort List	C++	Medium
149	Max Points on a Line	C++	Hard
150	Evaluate Reverse Polish Notation	C++	Medium
151	Reverse Words in a String	C++	Medium
152	Maximum Product Subarray	C++	Medium
153	Find Minimum in Rotated Sorted Array	C++	Medium
155	Min Stack	C++	Easy
160	Intersection of Two Linked Lists	C++	Easy
162	Find Peak Element	C++	Medium
165	Compare Version Numbers	C++	Medium
166	Fraction to Recurring Decimal	C++	Medium
167	Two Sum II - Input array is sorted	C++	Easy
168	Excel Sheet Column Title	C++	Easy
169	Majority Element	C++	Easy
171	Excel Sheet Column Number	C++	Easy
172	Factorial Trailing Zeroes	C++	Easy
179	Largest Number	C++	Medium
187	Repeated DNA Sequences	C++	Medium
188	Best Time to Buy and Sell Stock IV	C++	Hard
189	Rotate Array	C++	Easy
190	Reverse Bits	C++	Easy
191	Number of 1 Bits	C++	Easy
198	House Robber	C++	Easy
199	Binary Tree Right Side View	C++	Medium
200	Number of Islands	C++	Medium
201	Bitwise AND of Numbers Range	C++	Medium
202	Happy Number	C++	Easy
203	Remove Linked List Elements	C++	Easy
204	Count Primes	C++	Easy
205	Isomorphic Strings	C++	Easy
206	Reverse Linked List	C++	Easy
207	Course Schedule	C++	Medium
208	Implement Trie (Prefix Tree)	C++	Medium
209	Minimum Size Subarray Sum	C++	Medium
210	Course Schedule II	C++	Medium
211	Add and Search Word - Data structure design	C++	Medium
212	Word Search II	C++	Hard
213	House Robber II	C++	Medium
215	Kth Largest Element in an Array	C++	Medium
216	Combination Sum III	C++	Medium
217	Contains Duplicate	C++	Easy
218	The Skyline Problem	C++	Hard
219	Contains Duplicate II	C++	Easy
220	Contains Duplicate III	C++	Medium
221	Maximal Square	C++	Medium
222	Count Complete Tree Nodes	C++	Medium
223	Rectangle Area	C++	Medium
225	Implement Stack using Queues	C++	Easy
226	Invert Binary Tree	C++	Easy
227	Basic Calculator II	C++	Medium
228	Summary Ranges	C++	Medium
229	Majority Element II	C++	Medium
230	Kth Smallest Element in a BST	C++	Medium
231	Power of Two	C++	Easy
232	Implement Queue using Stacks	C++	Easy
233	Number of Digit One	C++	Hard
234	Palindrome Linked List	C++	Easy
235	Lowest Common Ancestor of a Binary Search Tree	C++	Easy
236	Lowest Common Ancestor of a Binary Tree	C++	Medium
237	Delete Node in a Linked List	C++	Easy
238	Product of Array Except Self	C++	Medium
239	Sliding Window Maximum	C++	Hard
240	Search a 2D Matrix II	C++	Medium
241	Different Ways to Add Parentheses	C++	Medium
242	Valid Anagram	C++	Easy
257	Binary Tree Paths	C++	Easy
258	Add Digits	C++	Easy
260	Single Number III	C++	Medium
263	Ugly Number	C++	Easy
264	Ugly Number II	C++	Medium
268	Missing Number	C++	Easy
274	H-Index	C++	Medium
275	H-Index II	C++	Medium
278	First Bad Version	C++	Easy
279	Perfect Squares	C++	Medium
283	Move Zeroes	C++	Easy
284	Peeking Iterator	C++	Medium
287	Find the Duplicate Number	C++	Medium
289	Game of Life	C++	Medium
290	Word Pattern	C++	Easy
292	Nim Game	C++	Easy
295	Find Median from Data Stream	C++	Hard
297	Serialize and Deserialize Binary Tree	C++	Hard
299	Bulls and Cows	C++	Medium
300	Longest Increasing Subsequence	C++	Medium
301	Remove Invalid Parentheses	C++	Hard
303	Range Sum Query - Immutable	C++	Easy
304	Range Sum Query 2D - Immutable	C++	Medium
306	Additive Number	C++	Medium
307	Range Sum Query - Mutable	C++	Medium
309	Best Time to Buy and Sell Stock with Cooldown	C++	Medium
310	Minimum Height Trees	C++	Medium
312	Burst Balloons	C++	Hard
313	Super Ugly Number	C++	Medium
315	Count of Smaller Numbers After Self	C++	Hard
316	Remove Duplicate Letters	C++	Medium
318	Maximum Product of Word Lengths	C++	Medium
319	Bulb Switcher	C++	Medium
322	Coin Change	C++	Medium
324	Wiggle Sort II	C++	Medium
326	Power of Three	C++	Easy
328	Odd Even Linked List	C++	Medium
329	Longest Increasing Path in a Matrix	C++	Hard
331	Verify Preorder Serialization of a Binary Tree	C++	Medium
332	Reconstruct Itinerary	C++	Medium
334	Increasing Triplet Subsequence	C++	Medium
337	House Robber III	C++	Medium
338	Counting Bits	C++	Medium
341	Flatten Nested List Iterator	C++	Medium
342	Power of Four	C++	Easy
343	Integer Break	C++	Medium
344	Reverse String	C++	Easy
345	Reverse Vowels of a String	C++	Easy
347	Top K Frequent Elements	C++	Medium
349	Intersection of Two Arrays	C++	Easy
350	Intersection of Two Arrays II	C++	Easy
357	Count Numbers with Unique Digits	C++	Medium
365	Water and Jug Problem	C++	Medium
367	Valid Perfect Square	C++	Easy
368	Largest Divisible Subset	C++	Medium
371	Sum of Two Integers	C++	Easy
372	Super Pow	C++	Medium
373	Find K Pairs with Smallest Sums	C++	Medium
374	Guess Number Higher or Lower	C++	Easy
375	Guess Number Higher or Lower II	C++	Medium
376	Wiggle Subsequence	C++	Medium
377	Combination Sum IV	C++	Medium
378	Kth Smallest Element in a Sorted Matrix	C++	Medium
380	Insert Delete GetRandom O(1)	C++	Medium
381	Insert Delete GetRandom O(1) - Duplicates allowed	C++	Hard
382	Linked List Random Node	C++	Medium
383	Ransom Note	C++	Easy
384	Shuffle an Array	C++	Medium
385	Mini Parser	C++	Medium
386	Lexicographical Numbers	C++	Medium
387	First Unique Character in a String	C++	Easy
388	Longest Absolute File Path	C++	Medium
389	Find the Difference	C++	Easy
390	Elimination Game	C++	Medium
392	Is Subsequence	C++	Easy
393	UTF-8 Validation	C++	Medium
394	Decode String	C++	Medium
395	Longest Substring with At Least K Repeating Characters	C++	Medium
396	Rotate Function	C++	Medium
397	Integer Replacement	C++	Medium
398	Random Pick Index	C++	Medium
400	Nth Digit	C++	Medium
401	Binary Watch	C++	Easy
402	Remove K Digits	C++	Medium
404	Sum of Left Leaves	C++	Easy
405	Convert a Number to Hexadecimal	C++	Easy
406	Queue Reconstruction by Height	C++	Medium
409	Longest Palindrome	C++	Easy
412	Fizz Buzz	C++	Easy
413	Arithmetic Slices	C++	Medium
414	Third Maximum Number	C++	Easy
415	Add Strings	C++	Easy
416	Partition Equal Subset Sum	C++	Medium
429	N-ary Tree Level Order Traversal	C++	Easy
434	Number of Segments in a String	C++	Easy
437	Path Sum III	C++	Easy
438	Find All Anagrams in a String	C++	Easy
441	Arranging Coins	C++	Easy
443	String Compression	C++	Easy
447	Number of Boomerangs	C++	Easy
448	Find All Numbers Disappeared in an Array	C++	Easy
453	Minimum Moves to Equal Array Elements	C++	Easy
454	4Sum II	C++	Medium
455	Assign Cookies	C++	Easy
459	Repeated Substring Pattern	C++	Easy
461	Hamming Distance	C++	Easy
463	Island Perimeter	C++	Easy
474	Ones and Zeroes	C++	Medium
475	Heaters	C++	Easy
476	Number Complement	C++	Easy
485	Max Consecutive Ones	C++	Easy
493	Reverse Pairs	C++	Hard
494	Target Sum	C++	Medium
496	Next Greater Element I	C++	Easy
500	Keyboard Row	C++	Easy
509	Fibonacci Number	C++	Easy
532	K-diff Pairs in an Array	C++	Easy
543	Diameter of Binary Tree	C++	Easy
560	Subarray Sum Equals K	C++	Medium
561	Array Partition I	C++	Easy
566	Reshape the Matrix	C++	Easy
572	Subtree of Another Tree	C++	Easy
581	Shortest Unsorted Continuous Subarray	C++	Easy
605	Can Place Flowers	C++	Easy
617	Merge Two Binary Trees	C++	Easy
621	Task Scheduler	C++	Medium
628	Maximum Product of Three Numbers	C++	Easy
643	Maximum Average Subarray I	C++	Easy
647	Palindromic Substrings	C++	Medium
661	Image Smoother	C++	Easy
665	Non-decreasing Array	C++	Easy
714	Best Time to Buy and Sell Stock with Transaction Fee	C++	Medium
739	Daily Temperatures	C++	Medium
829	Consecutive Numbers Sum	C++	Hard
846	Hand of Straights	C++	Medium
905	Sort Array By Parity	C++	Easy
946	Validate Stack Sequences	C++	Medium
1155	Number of Dice Rolls With Target Sum	C++	Medium