LeetCode

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LeetCode Problems

序号	标题	代码	题解	难度	备注
1	1. Two Sum	Java	题解	Easy
2	2. Add Two Numbers	Java	题解	Medium
3	3. Longest Substring Without Repeating Characters	Java	题解	Medium
4	4. Median of Two Sorted Arrays	Java	题解	Hard
5	5. Longest Palindromic Substring	Java	题解	Medium
6	6. ZigZag Conversion	Java	题解	Medium
7	7. Reverse Integer	Java	题解	Easy
8	8. String to Integer (atoi)	Java	题解	Medium
9	9. Palindrome Number	Java	题解	Easy
10	11. Container With Most Water	Java	题解	Medium
11	12. Integer to Roman	Java	题解	Medium
12	13. Roman to Integer	Java	题解	Easy
13	14. Longest Common Prefix	Java	题解	Easy
14	15. 3Sum	Java	题解	Medium	双指针
15	16. 3Sum Closest	Java	题解	Medium
16	17. Letter Combinations of a Phone Number	Java	题解	Medium
17	18. 4Sum	Java	题解	Medium	双指针
18	19. Remove Nth Node From End of List	Java	题解	Medium
19	20. Valid Parentheses	Java	题解	Easy
20	21. Merge Two Sorted Lists	Java	题解	Easy
21	22. Generate Parentheses	Java	题解	Medium
22	23. Merge k Sorted Lists	Java	题解	Hard
23	24. Swap Nodes in Pairs	Java	题解	Medium
24	26. Remove Duplicates from Sorted Array	Java	题解	Easy
25	27. Remove Element	Java	题解	Easy
26	28. Implement strStr()	Java	题解	Easy
27	29. Divide Two Integers	Java	题解	Medium
28	31. Next Permutation	Java	题解	Medium
29	33. Search in Rotated Sorted Array	Java	题解	Medium
30	34. Find First and Last Position of Element in Sorted Array	Java	题解	Medium
31	35. Search Insert Position	Java	题解	Easy
32	36. Valid Sudoku	Java	题解	Medium
33	37. Sudoku Solver	Java	题解	Hard
34	38. Count and Say	Java	题解	Easy
35	39. Combination Sum	Java	题解	Medium
36	40. Combination Sum II	Java	题解	Medium
37	41. First Missing Positive	Java	题解	Hard
38	42. Trapping Rain Water	Java	题解	Hard	单调栈
39	43. Multiply Strings	Java	题解	Medium
40	45. Jump Game II	Java	题解	Hard
41	46. Permutations	Java	题解	Medium
42	47. Permutations II	Java	题解	Medium
43	48. Rotate Image	Java	题解	Medium
44	49. Group Anagrams	Java	题解	Medium
45	50. Pow(x, n)	Java	题解	Medium
46	51. N-Queens	Java	题解	Hard
47	52. N-Queens II	Java	题解	Hard
48	53. Maximum Subarray	Java	题解	Easy
49	54. Spiral Matrix	Java	题解	Medium
50	55. Jump Game	Java	题解	Medium
51	56. Merge Intervals	Java	题解	Medium
52	57. Insert Interval	Java	题解	Hard
53	58. Length of Last Word	Java	题解	Easy
54	59. Spiral Matrix II	Java	题解	Medium
55	60. Permutation Sequence	Java	题解	Medium
56	61. Rotate List	Java	题解	Medium
57	62. Unique Paths	Java	题解	Medium
58	63. Unique Paths II	Java	题解	Medium
59	64. Minimum Path Sum	Java	题解	Medium
60	66. Plus One	Java	题解	Easy
61	67. Add Binary	Java	题解	Easy
62	69. Sqrt(x)	Java	题解	Easy
63	70. Climbing Stairs	Java	题解	Easy
64	71. Simplify Path	Java	题解	Medium
65	73. Set Matrix Zeroes	Java	题解	Medium
66	75. Sort Colors	Java	题解	Medium
67	76. Minimum Window Substring	Java	题解	Hard
68	77. Combinations	Java	题解	Medium
69	78. Subsets	Java	题解	Medium
70	79. Word Search	Java	题解	Medium
71	80. Remove Duplicates from Sorted Array II	Java	题解	Medium
72	81. Search in Rotated Sorted Array II	Java	题解	Medium
73	82. Remove Duplicates from Sorted List II	Java	题解	Medium
74	83. Remove Duplicates from Sorted List	Java	题解	Easy
75	86. Partition List	Java	题解	Medium
76	88. Merge Sorted Array	Java	题解	Easy
77	89. Gray Code	Java	题解	Medium
78	90. Subsets II	Java	题解	Medium
79	91. Decode Ways	Java	题解	Medium
80	92. Reverse Linked List II	Java	题解	Medium
81	93. Restore IP Addresses	Java	题解	Medium
82	94. Binary Tree Inorder Traversal	Java	题解	Medium
83	95. Unique Binary Search Trees II	Java	题解	Medium
84	96. Unique Binary Search Trees	Java	题解	Medium
85	98. Validate Binary Search Tree	Java	题解	Medium	树形DP套路或中序遍历
86	99. Recover Binary Search Tree	Java	题解	Medium	Morris遍历
87	100. Same Tree	Java	题解	Easy
88	101. Symmetric Tree	Java	题解	Easy
89	102. Binary Tree Level Order Traversal	Java	题解	Medium
90	103. Binary Tree Zigzag Level Order Traversal	Java	题解	Medium
91	104. Maximum Depth of Binary Tree	Java	题解	Easy
92	105. Construct Binary Tree from Preorder and Inorder Traversal	Java	题解	Medium	迭代如何实现？
93	106. Construct Binary Tree from Inorder and Postorder Traversal	Java	题解	Medium	迭代如何实现？
94	107. Binary Tree Level Order Traversal II	Java	题解	Easy
95	108. Convert Sorted Array to Binary Search Tree	Java	题解	Easy
96	109. Convert Sorted List to Binary Search Tree	Java	题解	Medium	分治+中序遍历
97	110. Balanced Binary Tree	Java	题解	Easy
98	111. Minimum Depth of Binary Tree	Java	题解	Easy	Morris解法需要深入研究
99	112. Path Sum	Java	题解	Easy
100	113. Path Sum II	Java	题解	Medium
101	114. Flatten Binary Tree to Linked List	Java	题解	Medium
102	116. Populating Next Right Pointers in Each Node	Java	题解	Medium
103	117. Populating Next Right Pointers in Each Node II	Java	题解	Medium
104	118. Pascal’s Triangle	Java	题解	Easy
105	119. Pascal’s Triangle II	Java	题解	Easy
106	120. Triangle	Java	题解	Medium
107	121. Best Time to Buy and Sell Stock	Java	题解	Easy
108	122. Best Time to Buy and Sell Stock II	Java	题解	Easy
109	123. Best Time to Buy and Sell Stock III	Java	题解	Hard
110	125. Valid Palindrome	Java	题解	Easy
111	127. Word Ladder	Java	题解	Medium
112	129. Sum Root to Leaf Numbers	Java	题解	Medium
113	130. Surrounded Regions	Java	题解	Medium
114	131. Palindrome Partitioning	Java	题解	Medium
115	133. Clone Graph	Java	题解	Medium
116	134. Gas Station	Java	题解	Medium
117	136. Single Number	Java	题解	Easy
118	138. Copy List with Random Pointer	Java	题解	Medium
119	139. Word Break	Java	题解	Medium
120	141. Linked List Cycle	Java	题解	Easy
121	142. Linked List Cycle II	Java	题解	Medium
122	144. Binary Tree Preorder Traversal	Java	题解	Medium
123	145. Binary Tree Postorder Traversal	Java	题解	Easy	强化迭代
124	146. LRU Cache	Java	题解	Medium
125	148. Sort List	Java	题解	Medium
126	150. Evaluate Reverse Polish Notation	Java	题解	Medium
127	151. Reverse Words in a String	Java	题解	Medium
128	152. Maximum Product Subarray	Java	题解	Medium
129	153. Find Minimum in Rotated Sorted Array	Java	题解	Medium
130	154. Find Minimum in Rotated Sorted Array II	Java	题解	Hard
131	155. Min Stack	Java	题解	Easy
132	160. Intersection of Two Linked Lists	Java	题解	Easy
133	162. Find Peak Element	Java	题解	Medium
134	166. Fraction to Recurring Decimal	Java	题解	Medium
135	167. Two Sum II - Input array is sorted	Java	题解	Easy
136	169. Majority Element	Java	题解	Easy
137	171. Excel Sheet Column Number	Java	题解	Easy
138	172. Factorial Trailing Zeroes	Java	题解	Easy
139	175. Combine Two Tables	SQL	题解	Easy
140	176. Second Highest Salary	SQL	题解	Easy
141	179. Largest Number	Java	题解	Medium
142	188. Best Time to Buy and Sell Stock IV	Java	题解	Hard
143	189. Rotate Array	Java	题解	Easy
144	190. Reverse Bits	Java	题解	Easy
145	191. Number of 1 Bits	Java	题解	Easy
146	198. House Robber	Java	题解	Easy
147	199. Binary Tree Right Side View	Java	题解	Medium	递归+DFS解法有意思
148	200. Number of Islands	Java	题解	Medium
149	202. Happy Number	Java	题解	Easy
150	204. Count Primes	Java	题解	Easy
151	205. Isomorphic Strings	Java	题解	Easy
152	206. Reverse Linked List	Java	题解	Easy
153	207. Course Schedule	Java	题解	Medium
154	208. Implement Trie (Prefix Tree)	Java	题解	Medium
155	210. Course Schedule II	Java	题解	Medium
156	215. Kth Largest Element in an Array	Java	题解	Medium
157	217. Contains Duplicate	Java	题解	Easy
158	221. Maximal Square	Java	题解	Medium
159	222. Count Complete Tree Nodes	Java	题解	Medium
160	226. Invert Binary Tree	Java	题解	Easy
161	227. Basic Calculator II	Java	题解	Medium
162	230. Kth Smallest Element in a BST	Java	题解	Medium
163	231. Power of Two	Java	题解	Easy
164	232. Implement Queue using Stacks	Java	题解	Easy
165	234. Palindrome Linked List	Java	题解	Easy
166	235. Lowest Common Ancestor of a Binary Search Tree	Java	题解	Easy	二叉搜索树左大右小的特性
167	236. Lowest Common Ancestor of a Binary Tree	Java	题解	Medium
168	237. Delete Node in a Linked List	Java	题解	Easy
169	238. Product of Array Except Self	Java	题解	Medium
170	239. Sliding Window Maximum	Java	题解	Hard
171	240. Search a 2D Matrix II	Java	题解	Medium
172	242. Valid Anagram	Java	题解	Easy
173	257. Binary Tree Paths	Java	题解	Easy
174	268. Missing Number	Java	题解	Easy
175	278. First Bad Version	Java	题解	Easy
176	279. Perfect Squares	Java	题解	Medium
177	283. Move Zeroes	Java	题解	Easy
178	287. Find the Duplicate Number	Java	题解	Medium
179	289. Game of Life	Java	题解	Medium
180	295. Find Median from Data Stream	Java	题解	Hard
181	297. Serialize and Deserialize Binary Tree	Java	题解	Hard	注意思维误区！
182	300. Longest Increasing Subsequence	Java	题解	Medium
183	303. Range Sum Query - Immutable	Java	题解	Easy
184	304. Range Sum Query 2D - Immutable	Java	题解	Medium
185	309. Best Time to Buy and Sell Stock with Cooldown	Java	题解	Medium
186	316. Remove Duplicate Letters	Java	题解	Hard
187	322. Coin Change	Java	题解	Medium
188	324. Wiggle Sort II	Java	题解	Medium
189	326. Power of Three	Java	题解	Easy
190	328. Odd Even Linked List	Java	题解	Medium
191	334. Increasing Triplet Subsequence	Java	题解	Medium
192	337. House Robber III	Java	题解	Medium
193	338. Counting Bits	Java	题解	Medium
194	341. Flatten Nested List Iterator	Java	题解	Medium
195	343. Integer Break	Java	题解	Medium
196	344. Reverse String	Java	题解	Easy
197	347. Top K Frequent Elements	Java	题解	Medium
198	350. Intersection of Two Arrays II	Java	题解	Easy
199	370. Range Addition	Java	题解	Medium	Plus专题
200	371. Sum of Two Integers	Java	题解	Easy
201	378. Kth Smallest Element in a Sorted Matrix	Java	题解	Medium
202	380. Insert Delete GetRandom O(1)	Java	题解	Medium
203	384. Shuffle an Array	Java	题解	Medium
204	387. First Unique Character in a String	Java	题解	Easy
205	394. Decode String	Java	题解	Medium
206	395. Longest Substring with At Least K Repeating Characters	Java	题解	Medium
207	402. Remove K Digits	Java	题解	Medium
208	404. Sum of Left Leaves	Java	题解	Easy
209	406. Queue Reconstruction by Height	Java	题解	Medium
210	409. Longest Palindrome	Java	题解	Easy
211	412. Fizz Buzz	Java	题解	Easy
212	416. Partition Equal Subset Sum	Java	题解	Medium
213	429. N-ary Tree Level Order Traversal	Java	题解	Medium	广度优先
214	437. Path Sum III	Java	题解	Medium	前缀和解法还需要多思考！
215	438. Find All Anagrams in a String	Java	题解	Medium
216	448. Find All Numbers Disappeared in an Array	Java	题解	Easy
217	450. Delete Node in a BST	Java	题解	Medium
218	453. Minimum Moves to Equal Array Elements	Java	题解	Medium
219	454. 4Sum II	Java	题解	Medium
220	462. Minimum Moves to Equal Array Elements II	Java	题解	Medium	快速选择
221	480. Sliding Window Median	Java	题解	Hard
222	494. Target Sum	Java	题解	Medium
223	496. Next Greater Element I	Java	题解	Easy
224	501. Find Mode in Binary Search Tree	Java	题解	Easy
225	503. Next Greater Element II	Java	题解	Medium
226	509. Fibonacci Number	Java	题解	Easy
227	513. Find Bottom Left Tree Value	Java	题解	Medium
228	515. Find Largest Value in Each Tree Row	Java	题解	Medium	层序遍历
229	523. Continuous Subarray Sum	Java	题解	Medium	前缀和
230	528. Random Pick with Weight	Java	题解	Medium
231	530. Minimum Absolute Difference in BST	Java	题解	Easy
232	538. Convert BST to Greater Tree	Java	题解	Easy
233	543. Diameter of Binary Tree	Java	题解	Easy
234	559. Maximum Depth of N-ary Tree	Java	题解	Easy
235	560. Subarray Sum Equals K	Java	题解	Medium	前缀和
236	567. Permutation in String	Java	题解	Medium
237	581. Shortest Unsorted Continuous Subarray	Java	题解	Easy
238	617. Merge Two Binary Trees	Java	题解	Easy
239	621. Task Scheduler	Java	题解	Medium
240	637. Average of Levels in Binary Tree	Java	题解	Easy
241	647. Palindromic Substrings	Java	题解	Medium
242	654. Maximum Binary Tree	Java	题解	Medium
243	669. Trim a Binary Search Tree	Java	题解	Easy
244	695. Max Area of Island	Java	题解	Medium
245	698. Partition to K Equal Sum Subsets	Java	题解	Medium
246	700. Search in a Binary Search Tree	Java	题解	Easy
247	701. Insert into a Binary Search Tree	Java	题解	Medium
248	704. Binary Search	Java	题解	Easy
249	710. Random Pick with Blacklist	Java	题解	Hard
250	713. Subarray Product Less Than K	Java	题解	Medium	滑动窗口
251	714. Best Time to Buy and Sell Stock with Transaction Fee	Java	题解	Medium
252	724. Find Pivot Index	Java	题解	Easy
253	739. Daily Temperatures	Java	题解	Medium
254	744. Find Smallest Letter Greater Than Target	Java	题解	Easy
255	746. Min Cost Climbing Stairs	Java	题解	Easy
256	752. Open the Lock	Java	题解	Medium
257	870. Advantage Shuffle	Java	题解	Medium
258	875. Koko Eating Bananas	Java	题解	Medium	二分查找
259	876. Middle of the Linked List	Java	题解	Easy
260	912. Sort an Array	Java	题解	Medium	归并，快排
261	931. Minimum Falling Path Sum	Java	题解	Medium
262	946. Validate Stack Sequences	Java	题解	Medium
263	992. Subarrays with K Different Integers	Java	题解	Hard
264	1011. Capacity To Ship Packages Within D Days	Java	题解	Medium
265	1094. Car Pooling	Java	题解	Medium
266	1109. Corporate Flight Bookings	Java	题解	Medium
267	1480. Running Sum of 1d Array	Java	题解	Easy
268	1644. Lowest Common Ancestor of a Binary Tree II	Java	题解	Medium	树形DP套路，没有验证答案！
269	1650. Lowest Common Ancestor of a Binary Tree III	Java	题解	Medium	链表相交
270	1823. Find the Winner of the Circular Game	Java	题解	Medium
271	1905. Count Sub Islands	Java	题解	Medium