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	25. Reverse Nodes in k-Group	Java	题解	Hard
25	26. Remove Duplicates from Sorted Array	Java	题解	Easy
26	27. Remove Element	Java	题解	Easy
27	28. 找出字符串中第一个匹配项的下标	Java	题解	Easy
28	29. Divide Two Integers	Java	题解	Medium
29	30. Substring with Concatenation of All Words	Java	题解	Hard
30	31. Next Permutation	Java	题解	Medium
31	32. Longest Valid Parentheses	Java	题解	Hard
32	33. Search in Rotated Sorted Array	Java	题解	Medium
33	34. Find First and Last Position of Element in Sorted Array	Java	题解	Medium
34	35. Search Insert Position	Java	题解	Easy
35	36. Valid Sudoku	Java	题解	Medium
36	37. Sudoku Solver	Java	题解	Hard
37	38. Count and Say	Java	题解	Easy
38	39. Combination Sum	Java	题解	Medium
39	40. Combination Sum II	Java	题解	Medium
40	41. First Missing Positive	Java	题解	Hard
41	42. Trapping Rain Water	Java	题解	Hard	单调栈
42	43. Multiply Strings	Java	题解	Medium
43	45. Jump Game II	Java	题解	Hard
44	46. Permutations	Java	题解	Medium
45	47. Permutations II	Java	题解	Medium
46	48. Rotate Image	Java	题解	Medium
47	49. Group Anagrams	Java	题解	Medium
48	50. Pow(x, n)	Java	题解	Medium
49	51. N-Queens	Java	题解	Hard
50	52. N-Queens II	Java	题解	Hard
51	53. Maximum Subarray	Java	题解	Medium
52	54. Spiral Matrix	Java	题解	Medium
53	55. Jump Game	Java	题解	Medium
54	56. Merge Intervals	Java	题解	Medium
55	57. Insert Interval	Java	题解	Hard
56	58. Length of Last Word	Java	题解	Easy
57	59. Spiral Matrix II	Java	题解	Medium
58	60. Permutation Sequence	Java	题解	Medium
59	61. Rotate List	Java	题解	Medium
60	62. Unique Paths	Java	题解	Medium
61	63. Unique Paths II	Java	题解	Medium
62	64. Minimum Path Sum	Java	题解	Medium
63	66. Plus One	Java	题解	Easy
64	67. Add Binary	Java	题解	Easy
65	69. Sqrt(x)	Java	题解	Easy
66	70. Climbing Stairs	Java	题解	Easy
67	71. Simplify Path	Java	题解	Medium
68	72. Edit Distance	Java	题解	Hard
69	73. Set Matrix Zeroes	Java	题解	Medium
70	74. Search a 2D Matrix	Java	题解	Medium
71	75. Sort Colors	Java	题解	Medium
72	76. Minimum Window Substring	Java	题解	Hard
73	77. Combinations	Java	题解	Medium
74	78. Subsets	Java	题解	Medium
75	79. Word Search	Java	题解	Medium
76	80. Remove Duplicates from Sorted Array II	Java	题解	Medium
77	81. Search in Rotated Sorted Array II	Java	题解	Medium
78	82. Remove Duplicates from Sorted List II	Java	题解	Medium
79	83. Remove Duplicates from Sorted List	Java	题解	Easy
80	84. Largest Rectangle in Histogram	Java	题解	Hard
81	86. Partition List	Java	题解	Medium
82	88. Merge Sorted Array	Java	题解	Easy
83	89. Gray Code	Java	题解	Medium
84	90. Subsets II	Java	题解	Medium
85	91. Decode Ways	Java	题解	Medium
86	92. Reverse Linked List II	Java	题解	Medium
87	93. Restore IP Addresses	Java	题解	Medium
88	94. Binary Tree Inorder Traversal	Java	题解	Medium
89	95. Unique Binary Search Trees II	Java	题解	Medium
90	96. Unique Binary Search Trees	Java	题解	Medium
91	98. Validate Binary Search Tree	Java	题解	Medium	树形DP套路或中序遍历
92	99. Recover Binary Search Tree	Java	题解	Medium	Morris遍历
93	100. Same Tree	Java	题解	Easy
94	101. Symmetric Tree	Java	题解	Easy
95	102. Binary Tree Level Order Traversal	Java	题解	Medium
96	103. Binary Tree Zigzag Level Order Traversal	Java	题解	Medium
97	104. Maximum Depth of Binary Tree	Java	题解	Easy
98	105. Construct Binary Tree from Preorder and Inorder Traversal	Java	题解	Medium	迭代如何实现？
99	106. Construct Binary Tree from Inorder and Postorder Traversal	Java	题解	Medium	迭代如何实现？
100	107. Binary Tree Level Order Traversal II	Java	题解	Easy
101	108. Convert Sorted Array to Binary Search Tree	Java	题解	Easy
102	109. Convert Sorted List to Binary Search Tree	Java	题解	Medium	分治+中序遍历
103	110. Balanced Binary Tree	Java	题解	Easy
104	111. Minimum Depth of Binary Tree	Java	题解	Easy	Morris解法需要深入研究
105	112. Path Sum	Java	题解	Easy
106	113. Path Sum II	Java	题解	Medium
107	114. Flatten Binary Tree to Linked List	Java	题解	Medium
108	115. Distinct Subsequences	Java	题解	Hard
109	116. Populating Next Right Pointers in Each Node	Java	题解	Medium
110	117. Populating Next Right Pointers in Each Node II	Java	题解	Medium
111	118. Pascal’s Triangle	Java	题解	Easy
112	119. Pascal’s Triangle II	Java	题解	Easy
113	120. Triangle	Java	题解	Medium
114	121. Best Time to Buy and Sell Stock	Java	题解	Easy
115	122. Best Time to Buy and Sell Stock II	Java	题解	Easy
116	123. Best Time to Buy and Sell Stock III	Java	题解	Hard
117	124. Binary Tree Maximum Path Sum	Java	题解	Hard
118	125. Valid Palindrome	Java	题解	Easy
119	127. Word Ladder	Java	题解	Medium
120	128. Longest Consecutive Sequence	Java	题解	Hard
121	129. Sum Root to Leaf Numbers	Java	题解	Medium
122	130. Surrounded Regions	Java	题解	Medium
123	131. Palindrome Partitioning	Java	题解	Medium
124	133. Clone Graph	Java	题解	Medium
125	134. Gas Station	Java	题解	Medium
126	135. Candy	Java	题解	Hard
127	136. Single Number	Java	题解	Easy
128	137. Single Number II	Java	题解	Medium
129	138. Copy List with Random Pointer	Java	题解	Medium
130	139. Word Break	Java	题解	Medium
131	140. Word Break II	Java	题解	Hard
132	141. Linked List Cycle	Java	题解	Easy
133	142. Linked List Cycle II	Java	题解	Medium
134	143. Reorder List	Java	题解	Medium
135	144. Binary Tree Preorder Traversal	Java	题解	Medium
136	145. Binary Tree Postorder Traversal	Java	题解	Easy	强化迭代
137	146. LRU Cache	Java	题解	Medium
138	148. Sort List	Java	题解	Medium
139	149. Max Points on a Line	Java	题解	Hard
140	150. Evaluate Reverse Polish Notation	Java	题解	Medium
141	151. Reverse Words in a String	Java	题解	Medium
142	152. Maximum Product Subarray	Java	题解	Medium
143	153. Find Minimum in Rotated Sorted Array	Java	题解	Medium
144	154. Find Minimum in Rotated Sorted Array II	Java	题解	Hard
145	155. Min Stack	Java	题解	Easy
146	160. Intersection of Two Linked Lists	Java	题解	Easy
147	162. Find Peak Element	Java	题解	Medium
148	166. Fraction to Recurring Decimal	Java	题解	Medium
149	167. Two Sum II - Input array is sorted	Java	题解	Easy
150	169. Majority Element	Java	题解	Easy
151	171. Excel Sheet Column Number	Java	题解	Easy
152	172. Factorial Trailing Zeroes	Java	题解	Easy
153	175. Combine Two Tables	SQL	题解	Easy
154	176. Second Highest Salary	SQL	题解	Easy
155	179. Largest Number	Java	题解	Medium
156	188. Best Time to Buy and Sell Stock IV	Java	题解	Hard
157	189. Rotate Array	Java	题解	Easy
158	190. Reverse Bits	Java	题解	Easy
159	191. Number of 1 Bits	Java	题解	Easy
160	198. House Robber	Java	题解	Easy
161	199. Binary Tree Right Side View	Java	题解	Medium	递归+DFS解法有意思
162	200. Number of Islands	Java	题解	Medium
163	202. Happy Number	Java	题解	Easy
164	203. Remove Linked List Elements	Java	题解	Easy
165	204. Count Primes	Java	题解	Easy
166	205. Isomorphic Strings	Java	题解	Easy
167	206. Reverse Linked List	Java	题解	Easy
168	207. Course Schedule	Java	题解	Medium
169	208. Implement Trie (Prefix Tree)	Java	题解	Medium
170	209. Minimum Size Subarray Sum	Java	题解	Medium
171	210. Course Schedule II	Java	题解	Medium
172	211. 添加与搜索单词 - 数据结构设计	Java	题解	Medium
173	213. House Robber II	Java	题解	Medium
174	215. Kth Largest Element in an Array	Java	题解	Medium
175	216. Combination Sum III	Java	题解	Medium
176	217. Contains Duplicate	Java	题解	Easy
177	221. Maximal Square	Java	题解	Medium
178	222. Count Complete Tree Nodes	Java	题解	Medium
179	224. Basic Calculator	Java	题解	Hard
180	226. Invert Binary Tree	Java	题解	Easy
181	227. Basic Calculator II	Java	题解	Medium
182	230. Kth Smallest Element in a BST	Java	题解	Medium
183	231. Power of Two	Java	题解	Easy
184	232. Implement Queue using Stacks	Java	题解	Easy
185	234. Palindrome Linked List	Java	题解	Easy
186	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
187	236. Lowest Common Ancestor of a Binary Tree	Java	题解	Medium
188	237. Delete Node in a Linked List	Java	题解	Easy
189	238. Product of Array Except Self	Java	题解	Medium
190	239. Sliding Window Maximum	Java	题解	Hard
191	240. Search a 2D Matrix II	Java	题解	Medium
192	242. Valid Anagram	Java	题解	Easy
193	257. Binary Tree Paths	Java	题解	Easy
194	260. Single Number III	Java	题解	Medium
195	268. Missing Number	Java	题解	Easy
196	278. First Bad Version	Java	题解	Easy
197	279. Perfect Squares	Java	题解	Medium
198	283. Move Zeroes	Java	题解	Easy
199	287. Find the Duplicate Number	Java	题解	Medium
200	289. Game of Life	Java	题解	Medium
201	295. Find Median from Data Stream	Java	题解	Hard
202	297. Serialize and Deserialize Binary Tree	Java	题解	Hard	注意思维误区！
203	300. Longest Increasing Subsequence	Java	题解	Medium
204	303. Range Sum Query - Immutable	Java	题解	Easy
205	304. Range Sum Query 2D - Immutable	Java	题解	Medium
206	309. Best Time to Buy and Sell Stock with Cooldown	Java	题解	Medium
207	316. Remove Duplicate Letters	Java	题解	Hard
208	322. Coin Change	Java	题解	Medium
209	324. Wiggle Sort II	Java	题解	Medium
210	326. Power of Three	Java	题解	Easy
211	328. Odd Even Linked List	Java	题解	Medium
212	334. Increasing Triplet Subsequence	Java	题解	Medium
213	337. House Robber III	Java	题解	Medium
214	338. Counting Bits	Java	题解	Medium
215	341. Flatten Nested List Iterator	Java	题解	Medium
216	343. Integer Break	Java	题解	Medium
217	344. Reverse String	Java	题解	Easy
218	347. Top K Frequent Elements	Java	题解	Medium
219	350. Intersection of Two Arrays II	Java	题解	Easy
220	370. Range Addition	Java	题解	Medium	Plus专题
221	371. Sum of Two Integers	Java	题解	Easy
222	378. Kth Smallest Element in a Sorted Matrix	Java	题解	Medium
223	380. Insert Delete GetRandom O(1)	Java	题解	Medium
224	384. Shuffle an Array	Java	题解	Medium
225	387. First Unique Character in a String	Java	题解	Easy
226	392. Is Subsequence	Java	题解	Easy
227	394. Decode String	Java	题解	Medium
228	395. Longest Substring with At Least K Repeating Characters	Java	题解	Medium
229	400. Nth Digit	Java	题解	Medium
230	402. Remove K Digits	Java	题解	Medium
231	404. Sum of Left Leaves	Java	题解	Easy
232	406. Queue Reconstruction by Height	Java	题解	Medium
233	409. Longest Palindrome	Java	题解	Easy
234	412. Fizz Buzz	Java	题解	Easy
235	415. Add Strings	Java	题解	Easy
236	416. Partition Equal Subset Sum	Java	题解	Medium
237	429. N-ary Tree Level Order Traversal	Java	题解	Medium	广度优先
238	437. Path Sum III	Java	题解	Medium	前缀和解法还需要多思考！
239	438. Find All Anagrams in a String	Java	题解	Medium
240	448. Find All Numbers Disappeared in an Array	Java	题解	Easy
241	450. Delete Node in a BST	Java	题解	Medium
242	453. Minimum Moves to Equal Array Elements	Java	题解	Medium
243	454. 4Sum II	Java	题解	Medium
244	462. Minimum Moves to Equal Array Elements II	Java	题解	Medium	快速选择
245	474. Ones and Zeroes	Java	题解	Medium
246	480. Sliding Window Median	Java	题解	Hard
247	494. Target Sum	Java	题解	Medium
248	496. Next Greater Element I	Java	题解	Easy
249	501. Find Mode in Binary Search Tree	Java	题解	Easy
250	503. Next Greater Element II	Java	题解	Medium
251	509. Fibonacci Number	Java	题解	Easy
252	513. Find Bottom Left Tree Value	Java	题解	Medium
253	515. Find Largest Value in Each Tree Row	Java	题解	Medium	层序遍历
254	516. Longest Palindromic Subsequence	Java	题解	Medium
255	523. Continuous Subarray Sum	Java	题解	Medium	前缀和
256	528. Random Pick with Weight	Java	题解	Medium
257	530. Minimum Absolute Difference in BST	Java	题解	Easy
258	538. Convert BST to Greater Tree	Java	题解	Easy
259	543. Diameter of Binary Tree	Java	题解	Easy
260	547. 省份数量	Java	题解	Medium
261	559. Maximum Depth of N-ary Tree	Java	题解	Easy
262	560. Subarray Sum Equals K	Java	题解	Medium	前缀和
263	567. Permutation in String	Java	题解	Medium
264	581. Shortest Unsorted Continuous Subarray	Java	题解	Easy
265	617. Merge Two Binary Trees	Java	题解	Easy
266	621. Task Scheduler	Java	题解	Medium
267	637. Average of Levels in Binary Tree	Java	题解	Easy
268	647. Palindromic Substrings	Java	题解	Medium
269	649. Dota2 Senate	Java	题解	Medium
270	654. Maximum Binary Tree	Java	题解	Medium
271	662. Maximum Width of Binary Tree	Java	题解	Medium
272	669. Trim a Binary Search Tree	Java	题解	Easy
273	670. Maximum Swap	Java	题解	Medium
274	695. Max Area of Island	Java	题解	Medium
275	697. Degree of an Array	Java	题解	Easy
276	698. Partition to K Equal Sum Subsets	Java	题解	Medium
277	700. Search in a Binary Search Tree	Java	题解	Easy
278	701. Insert into a Binary Search Tree	Java	题解	Medium
279	704. Binary Search	Java	题解	Easy
280	705. Design HashSet	Java	题解	Easy
281	707. Design Linked List	Java	题解	Medium
282	710. Random Pick with Blacklist	Java	题解	Hard
283	713. Subarray Product Less Than K	Java	题解	Medium	滑动窗口
284	714. Best Time to Buy and Sell Stock with Transaction Fee	Java	题解	Medium
285	718. Maximum Length of Repeated Subarray	Java	题解	Medium
286	721. Accounts Merge	Java	题解	Medium
287	724. Find Pivot Index	Java	题解	Easy
288	739. Daily Temperatures	Java	题解	Medium
289	740. Delete and Earn	Java	题解	Medium
290	744. Find Smallest Letter Greater Than Target	Java	题解	Easy
291	746. Min Cost Climbing Stairs	Java	题解	Easy
292	752. Open the Lock	Java	题解	Medium
293	768. Max Chunks To Make Sorted II	Java	题解	Hard
294	787. Cheapest Flights Within K Stops	Java	题解	Medium
295	794. Valid Tic-Tac-Toe State	Java	题解	Medium
296	796. Rotate String	Java	题解	Easy
297	841. Keys and Rooms	Java	题解	Medium
298	865. Smallest Subtree with all the Deepest Nodes	Java	题解	Medium
299	869. Reordered Power of 2	Java	题解	Medium
300	870. Advantage Shuffle	Java	题解	Medium
301	875. Koko Eating Bananas	Java	题解	Medium	二分查找
302	876. Middle of the Linked List	Java	题解	Easy
303	881. Boats to Save People	Java	题解	Medium
304	890. Find and Replace Pattern	Java	题解	Medium
305	892. Surface Area of 3D Shapes	Java	题解	Easy
306	900. RLE Iterator	Java	题解	Medium
307	904. Fruit Into Baskets	Java	题解	Medium
308	912. Sort an Array	Java	题解	Medium	归并，快排
309	915. Partition Array into Disjoint Intervals	Java	题解	Medium
310	918. Maximum Sum Circular Subarray	Java	题解	Medium
311	926. Flip String to Monotone Increasing	Java	题解	Medium
312	931. Minimum Falling Path Sum	Java	题解	Medium
313	946. Validate Stack Sequences	Java	题解	Medium
314	980. Unique Paths III	Java	题解	Hard
315	986. Interval List Intersections	Java	题解	Medium
316	992. Subarrays with K Different Integers	Java	题解	Hard
317	994. Rotting Oranges	Java	题解	Easy
318	1006. Clumsy Factorial	Java	题解	Medium
319	1007. Minimum Domino Rotations For Equal Row	Java	题解	Medium
320	1011. Capacity To Ship Packages Within D Days	Java	题解	Medium
321	1020. Number of Enclaves	Java	题解	Medium
322	1022. Sum of Root To Leaf Binary Numbers	Java	题解	Easy
323	1023. Camelcase Matching	Java	题解	Medium
324	1033. Moving Stones Until Consecutive	Java	题解	Easy
325	1041. Robot Bounded In Circle	Java	题解	Medium
326	1047. Remove All Adjacent Duplicates In String	Java	题解	Easy
327	1049. Last Stone Weight II	Java	题解	Medium
328	1052. Grumpy Bookstore Owner	Java	题解	Medium
329	1081. Smallest Subsequence of Distinct Characters	Java	题解	Medium
330	1090. Largest Values From Labels	Java	题解	Medium	排序规则跟 179、870 题类似：保存下标，使用其他数组的值对下标数组进行排序。
331	1094. Car Pooling	Java	题解	Medium
332	1104. Path In Zigzag Labelled Binary Tree	Java	题解	Medium
333	1109. Corporate Flight Bookings	Java	题解	Medium
334	1110. Delete Nodes And Return Forest	Java	题解	Medium
335	1137. N-th Tribonacci Number	Java	题解	Easy
336	1143. Longest Common Subsequence	Java	题解	Medium
337	1171. Remove Zero Sum Consecutive Nodes from Linked List	Java	题解	Medium
338	1189. Maximum Number of Balloons	Java	题解	Easy
339	1209. Remove All Adjacent Duplicates in String II	Java	题解	Medium
340	1217. 玩筹码	Java	题解	Easy
341	1253. Reconstruct a 2-Row Binary Matrix	Java	题解	Medium
342	1289. Minimum Falling Path Sum II	Java	题解	Hard
343	1325. Delete Leaves With a Given Value	Java	题解	Medium
344	1349. Maximum Students Taking Exam	Java	题解	Hard
345	1362. Closest Divisors	Java	题解	Medium
346	1382. Balance a Binary Search Tree	Java	题解	Medium
347	1387. Sort Integers by The Power Value	Java	题解	Medium
348	1400. Construct K Palindrome Strings	Java	题解	Medium
349	1410. HTML Entity Parser	Java	题解	Medium
350	1442. Count Triplets That Can Form Two Arrays of Equal XOR	Java	题解	Medium
351	1457. Pseudo-Palindromic Paths in a Binary Tree	Java	题解	Medium
352	1480. Running Sum of 1d Array	Java	题解	Easy
353	1496. Path Crossing	Java	题解	Easy
354	1509. Minimum Difference Between Largest and Smallest Value in Three Moves	Java	题解	Medium
355	1530. Number of Good Leaf Nodes Pairs	Java	题解	Medium
356	1561. Maximum Number of Coins You Can Get	Java	题解	Medium
357	1644. Lowest Common Ancestor of a Binary Tree II	Java	题解	Medium	树形DP套路，没有验证答案！
358	1650. Lowest Common Ancestor of a Binary Tree III	Java	题解	Medium	链表相交
359	1700. Number of Students Unable to Eat Lunch	Java	题解	Easy
360	1769. Minimum Number of Operations to Move All Balls to Each Box	Java	题解	Medium
361	1823. Find the Winner of the Circular Game	Java	题解	Medium
362	1839. Longest Substring Of All Vowels in Order	Java	题解	Medium
363	1864. Minimum Number of Swaps to Make the Binary String Alternating	Java	题解	Medium
364	1905. Count Sub Islands	Java	题解	Medium
365	1997. First Day Where You Have Been in All the Rooms	Java	题解	Medium