LeetCode collection.
| Date | Question Numbers | ✨ Star ! |
|---|---|---|
| 数组和动态数组 | ||
| 73. Set Matrix Zeroes | ||
| 48. Rotate Image | ||
| 344. Reverse String | ||
| 414. Third Maximum Number | ||
| 448. Find All Numbers Disappeared in an Array | ||
| 66. Plus One | ||
| 238. Product of Array Except Self | ||
| 697. Degree of an Array | ||
| 849. Maximize Distance to Closest Person | ||
| 189. Rotate Array | ||
| Lint-39. Recover Rotated Sorted Array 三步翻转法 ！！！！ | ||
| 54. Spiral Matrix | ||
| 递归 | ||
| 784. Letter Case Permutation | ||
| 31. Next Permutation | ||
| 二分搜索 | ||
| 50. Pow(x, n) | ||
| 34. Find First and Last Position of Element in Sorted Array | 1-yes | |
| 35. Search Insert Position | 1-yes | |
| 658. Find K Closest Elements | 1-no | |
| 33. Search in Rotated Sorted Array | 1-no | |
| 81. Search in Rotated Sorted Array II | 1-no | |
| 153. Find Minimum in Rotated Sorted Array | ||
| 154. Find Minimum in Rotated Sorted Array II | ||
| 702. Search in a Sorted Array of Unknown Size 这个题定量分析 ！ | 1-no | |
| 74. Search a 2D Matrix | 1-no | |
| 240. Search a 2D Matrix II | 1-no | |
| 162. Find Peak Element | 1-no | |
| 69. Sqrt(x) | 1-yes | |
| Lint-586. Sqrt(x) II | ||
| 4. Median of Two Sorted Array 和下面的题是一样的 | ||
| Lint-931. Median of K Sorted Arrays | ||
| Laicode: Kth Smallest In Two Sorted Arrays 这个题非常重要！可以到 logn+logk | bilibili | |
| 7. Reverse Integer | ||
| 475. Heaters | ||
| 57. Insert Interval | ||
| 349. Intersection of Two Arrays | ||
| Lint-140. Fast Power | ||
| 378. Kth Smallest Element in a Sorted Matrix 二分中的逼近法 | ||
| 302. Smallest Rectangle Enclosing Black Pixels 二分中的逼近法 | ||
| Lint-183. Wood Cut | ||
| 经验：并不是所有二分法都适用于 left+1<right, 对于可以排除mid的问题，使用left<=right更简便 | ||
| 线段树 segment tree | ||
| Lint-201. Segment Tree Build | ||
| Lint-439. Segment Tree Build II | max的，触底反弹 | |
| Lint-202. Segment Tree Query | ||
| Lint-247. Segment Tree Query II | ||
| Lint-203. Segment Tree Modify | ||
| 206. Interval Sum | ||
| 207. Interval Sum II | ||
| 248. Count of Smaller Number | ||
| 249. Count of Smaller Number before itself | ||
| 307. Range Sum Query - Mutable 还没做 | ||
| 817. Range Sum Query 2D - Mutable | ||
| 665. Range Sum Query 2D - Immutable | ||
| 扫描线 | ||
| Lint-391. Number of Airplanes in the Sky | ||
| 218. The Skyline Problem | ||
| 253. Meeting Rooms II | ||
| 排序 | ||
| 969. Pancake Sorting | ||
| 347. Top K Frequent Elements 桶排序 | ||
| 296. Best Meeting Point | ||
| Lint-139. Subarray Sum Closest | ||
| 643. Maximum Average Subarray I | ||
| 644. Maximum Average Subarray II 二分法，尺举法 | ||
| Lint-64. Merge Sorted Array | ||
| 56. Merge Intervals | 关键是保证开头是sort | |
| Lint-577. Merge K Sorted Interval Lists | ||
| 280. Wiggle Sort | ||
| 324. Wiggle Sort II 不会 | ||
| 164. Maximum Gap | ||
| 归并变种 | ||
| 493. Reverse Pairs 归并排序 | ||
| --- | ||
| 快排变种 | ||
| 215. Kth Largest Element in an Array | ||
| Lint-143. Sort Colors II 彩虹排序 | ||
| 分治法 | ||
| 349. Intersection of Two Arrays | ||
| 350. Intersection of Two Arrays II | ||
| 53.Maximum Subarray 这题实际是动态规划 | ||
| 311. Sparse Matrix Multiplication | ||
| 523. Continuous Subarray Sum | ||
| 241. Different Ways to Add Parentheses 分治，递归 | ||
| 链表 | ||
| 237. Delete Node in a Linked List | ||
| 876. Middle of the Linked List | ||
| 141. Linked List Cycle | ||
| 142. Linked List Cycle II (找到环的开始) | ||
| 19. Remove Nth Node From End of List | ||
| 21. Merge Two Sorted Lists | ||
| 160. Intersection of Two Linked Lists | ||
| 147. Insertion Sort List | ||
| 148. Sort List | ||
| 86. Partition List | ||
| 206. Reverse Linked List | ||
| 92. Reverse Linked List II | ||
| 25. Reverse Nodes in k-Group | 没做出来，要重新看一遍 | |
| 234. Palindrome Linked List 回文 | 不会 | |
| 83. Remove Duplicates from Sorted List | ||
| 82. Remove Duplicates from Sorted List II | ||
| 61. Rotate List 还没做 | ||
| 24. Swap Nodes in Pairs | ||
| 堆栈和队列 | ||
| 32. Longest Valid Parentheses | ||
| 71. Simplify Path | ||
| 394. Decode String | ||
| 682. Baseball Game | ||
| 735. Asteroid Collision | ||
| 239. Sliding Window Maximum 还没做，优先考虑用队列的方法 | ||
| 224. Basic Calculator | ||
| 456. 132 Pattern | ||
| 402. Remove K Digits | ||
| 946. Validate Stack Sequences | ||
| 621. Task Scheduler 还没做 | ||
| 622. Design Circular Queue 还没做 | ||
| 973. K Closest Points to Origin | ||
| 栈 Stack | 栈的精髓：把 递归中最后处理 的 压在最前面 | |
| 232. Implement Queue using Stacks | ||
| 225. Implement Stack using Queues | ||
| 20. Valid Parentheses | ||
| 150. Evaluate Reverse Polish Notation 反波兰表达式 | ||
| 155. Min Stack | ||
| Lint-22. Flatten List | ||
| 341. Flatten Nested List Iterator | ||
| 251. Flatten 2D Vector | ||
| 单调栈 | ||
| 739. Daily Temperatures | ||
| 1019. Next Greater Node In Linked List | ||
| 496. Next Greater Element I 单调栈 | ||
| 503. Next Greater Element II | ||
| 84. Largest Rectangle in Histogram | ||
| 85. Maximal Rectangle | ||
| 654. Maximum Binary Tree 单调栈 经典～！！ | ||
| Lint-367. Expression Tree Build 和leetcode654一样 | ||
| Lint-368. Expression Evaluation 中缀变后缀表达式再计算 | ||
| ---- | ||
| 队列 queue | ||
| Lint-230. Animal Shelter 双端队列，链表 | ||
| 346. Moving Average from Data Stream | ||
| 239. Sliding Window Maximum | ||
| 哈希表 | ||
| 387. First Unique Character in a String 这题要用过一遍的方法！非常重要！ | ||
| 146. LRU Cache | ||
| Lint-685. First Unique Number in Data Stream | ||
| 349. Intersection of Two Arrays | ||
| 350. Intersection of Two Arrays II | ||
| 771. Jewels and Stones | ||
| 217. Contains Duplicate | ||
| 219. Contains Duplicate II | ||
| 811. Subdomain Visit Count | ||
| 500. Keyboard Row | ||
| 380. Insert Delete GetRandom O(1) | ||
| 36. Valid Sudoku | ||
| Lint-594. strStr II 这题不用会 | https://www.jiuzhang.com/video/rabin-karp | |
| Lint-138. Subarray Sum | ||
| Lint-404. Subarray Sum II | ||
| Lint-405. Submatrix Sum | ||
| Lint-944. Maximum Submatrix | 和53一样，降维攻击 | |
| 560. Subarray Sum Equals K | ||
| 53. Maximum Subarray 前缀和 | ||
| Lint-558. Sliding Window Matrix Maximum | ||
| 堆 | ||
| 215. Kth Largest Element in an Array | y | |
| 692. Top K Frequent Words | ||
| 263. Ugly Number | ||
| 264. Ugly Number II | ||
| 373. Find K Pairs with Smallest Sums | n | |
| 23. Merge k Sorted Lists | ||
| 295. Find Median from Data Stream | ||
| 480. Sliding Window Median | ||
| 502. IPO | ||
| 451. Sort Characters By Frequency 还没做 | ||
| 871. Minimum Number of Refueling Stops 还没做 | ||
| 407. Trapping Rain Water II | ||
| 378. Kth Smallest Element in a Sorted Matrix | klogk | |
| 42. Trapping Rain Water 单调栈 | ||
| 407. Trapping Rain Water II | ||
| 树 | ||
| 二叉树 | ||
| 270. Closest Binary Search Tree Value | ||
| 272. Closest Binary Search Tree Value II | ||
| 114. Flatten Binary Tree to Linked List | ||
| 110. Balanced Binary Tree | ||
| 98. Validate Binary Search Tree 判断二叉搜索树 | ||
| 173. Binary Search Tree Iterator | ||
| 235. Lowest Common Ancestor of a Binary Search Tree | ||
| 236. Lowest Common Ancestor of a Binary Tree | ||
| 108. Convert Sorted Array to Binary Search Tree | ||
| 109. Convert Sorted List to Binary Search Tree | ||
| 298. Binary Tree Longest Consecutive Sequence | ||
| 549. Binary Tree Longest Consecutive Sequence II | ||
| 958. Check Completeness of a Binary Tree | ||
| ---- | ||
| 104. Maximum Depth of Binary Tree | ||
| 110. Balanced Binary Tree | ||
| 101. Symmetric Tree | ||
| 100. Same Tree | ||
| 700. Search in a Binary Search Tree | ||
| 450. Delete Node in a BST | ||
| 701. Insert into a Binary Search Tree 见算法导论 165 | ||
| 94. Binary Tree Inorder Traversal 用栈实现iterative | ||
| 230. Kth Smallest Element in a BST 用栈实现inorder遍历 | ||
| 144. Binary Tree Preorder Traversal | ||
| 145. Binary Tree Postorder Traversal | 栈的精髓：把 递归中最后处理 的 压在最前面 | |
| 102. Binary Tree Level Order Traversal 这个一道BFS,和773对比 | ||
| 107. Binary Tree Level Order Traversal II | ||
| 513. Find Bottom Left Tree Value | ||
| 103. Binary Tree Zigzag Level Order Traversal | ||
| 105. Construct Binary Tree from Preorder and Inorder Traversal 这题不太理解本质 | ||
| 111. Minimum Depth of Binary Tree | ||
| 257. Binary Tree Paths | ||
| 112. Path Sum | ||
| 113. Path Sum II | ||
| 437. Path Sum III | ||
| 124. Binary Tree Maximum Path Sum | ||
| Lint-472. Binary Tree Path Sum III 二叉树无向图的构建 | ||
| 450. Delete Node in a BST 还没做 | ||
| 938. Range Sum of BST 还没做 | ||
| 图论 | ||
| 宽度优先搜索 | 重要：能用BFS做的题，就不要用DFS！ | |
| 200. Number of Islands | ||
| Lint-611. Knight Shortest Path 用字典可以记录 见过的点，和对应距离 | ||
| 133. Clone Graph | ||
| 297. Serialize and Deserialize Binary Tree 这个题还是有点蒙 | ||
| 127. Word Ladder | ||
| 126. Word Ladder II | ||
| Lint-794. Sliding Puzzle II | ||
| 773. Sliding Puzzle 处理二维矩阵的技巧 | ||
| 102. Binary Tree Level Order Traversal 这个一道BFS,和773对比 | ||
| Lint-531. Six Degrees | ||
| Lint-573. Build Post Office II | ||
| 752. Open the Lock | ||
| 拓扑排序 | ||
| 207. Course Schedule | ||
| 210. Course Schedule II | ||
| Lint-815. Course Schedule IV 还不会！！！ | ||
| 444. Sequence Reconstruction | ||
| Lint-127. Topological Sorting | ||
| ---- | ||
| 深度优先搜索 | ||
| 回溯法 | 在不能继续搜索的点，直接return | |
| 22. Generate Parentheses | ||
| 17. Letter Combinations of a Phone Number 回溯法 | ||
| 46. Permutations | ||
| 47. Permutations II | ||
| 60. Permutation Sequence | ||
| 39. Combination Sum 回溯法 | ||
| 40. Combination Sum II | ||
| 78. Subsets | ||
| 90. Subsets II | ||
| 51. N-Queens | ||
| 290. Word Pattern | ||
| 291. Word Pattern II 回溯 | ||
| 79. Word Search | ||
| 294. Flip Game II | ||
| --- | ||
| 490. The Maze | ||
| 505. The Maze II | 黑色（已经pop出来的,才放seen）不压栈，不压队。Dijkstra是BFS | |
| 499. The Maze III | ||
| 733. Flood Fill | ||
| 547. Friend Circles | ||
| 695. Max Area of Island | stack,queue,只要append完了，立刻放seen | |
| 690. Employee Importance | ||
| 785. Is Graph Bipartite? | 涂颜色 | |
| 417. Pacific Atlantic Water Flow | ||
| 542. 01 Matrix | n 不会 | |
| 721. Accounts Merge | 考察点，把数据转换成图 | |
| 210. Course Schedule II | ||
| 630. Course Schedule III | ||
| 997. Find the Town Judge | ||
| 407. Trapping Rain Water II 还没做 | ||
| 743. Network Delay Time | ||
| 282. Expression Add Operators 这个题好多的边界条件 | ||
| 301. Remove Invalid Parentheses BFS剪枝 | ||
| 并查集 | ||
| 261. Graph Valid Tree | ||
| 130. Surrounded Regions | ||
| 128. Longest Consecutive Sequence | ||
| Lint-629. Minimum Spanning Tree 最小生成树，Kruskal算法 | ||
| 684. Redundant Connection | ||
| 305. Number of Islands II 很重要的并查集的题 | ||
| Lint-589. Connecting Graph | ||
| Lint-590. Connecting Graph II | ||
| Lint-591. Connecting Graph III | ||
| Lint-432. Find the Weak Connected Component in the Directed Graph 最后一块没看懂 | ||
| 721. Accounts Merge | ||
| 双指针 | ||
| 287. Find the Duplicate Number 兔子和乌龟 | ||
| 170. Two Sum III - Data structure design | ||
| 283. Move Zeroes | ||
| 26. Remove Duplicates from Sorted Array 兔子乌龟 | ||
| 344. Reverse String | ||
| 1. Two Sum 其实这个是哈希表 | ||
| 167. Two Sum II - Input array is sorted | ||
| 15. 3Sum | ||
| 16. 3Sum Closest | ||
| 18. 4Sum | ||
| 21. Merge Two Sorted Lists | ||
| 349. Intersection of Two Arrays | ||
| 523. Continuous Subarray Sum | ||
| Lint-402. Continuous Subarray Sum | ||
| Lint-403. Continuous Subarray Sum II | ||
| 169. Majority Element | ||
| 229. Majority Element II 摩尔投票算法 | ||
| 75. Sort Colors 荷兰国旗：很经典的一道题 | ||
| Lint-143. Sort Colors II | ||
| 11. Container With Most Water 装水的题 | ||
| 42. Trapping Rain Water | 不会 | |
| 125. Valid Palindrome | ||
| 986. Interval List Intersections | ||
| Lint-839. Merge Two Sorted Interval Lists | ||
| 滑动窗口 | ||
| 845. Longest Mountain in Array | 未做 | |
| 26. Remove Duplicates from Sorted Array | ||
| 80. Remove Duplicates from Sorted Array II | ||
| 27. Remove Element | ||
| 28. Implement strStr() | ||
| 713. Subarray Product Less Than K | ||
| 438. Find All Anagrams in a String | ||
| 159. Longest Substring with At Most Two Distinct Characters | 还没做 | |
| 340. Longest Substring with At Most K Distinct Characters | 还没做 | |
| 239. Sliding Window Maximum 可以用堆 | 还没做 | |
| 480. Sliding Window Median | ||
| 同向双指针 | ||
| 209. Minimum Size Subarray Sum | 同向双指针 | |
| 3. Longest Substring Without Repeating Characters | ||
| 76. Minimum Window Substring | ||
| 340. Longest Substring with At Most K Distinct Characters | ||
| 动态规划 | ||
| 198. House Robber | ||
| 213. House Robber II | ||
| 337. House Robber III | ||
| 746. Min Cost Climbing Stairs | ||
| 96. Unique Binary Search Trees | 科特兰数 | |
| 714. Best Time to Buy and Sell Stock with Transaction Fee | ||
| 70. Climbing Stairs | ||
| 276. Paint Fence | ||
| 368. Largest Divisible Subset | ||
| 343. Integer Break | ||
| 583. Delete Operation for Two Strings | ||
| 877. Stone Game | ||
| 1140. Stone Game II | ||
| 记忆化搜索 | ||
| 139. Word Break | ||
| 140. Word Break II | ||
| Lint-683. Word Break III | ||
| 九章算法 动态规划： | ||
| 322. Coin Change 典型 | ||
| 62. Unique Paths 计数型动态规划 | ||
| 63. Unique Paths II 坐标型动态规划 | ||
| 55. Jump Game 存在型动态规划 | ||
| 152. Maximum Product Subarray | ||
| 91. Decode Ways 划分型动态规划 | ||
| 64. Minimum Path Sum 坐标型 (可以用滚动数组节省空间) | ||
| 361. Bomb Enemy 坐标型 | ||
| 674. Longest Continuous Increasing Subsequence | ||
| 329. Longest Increasing Path in a Matrix | ||
| 338. Counting Bits | ||
| 序列型动态规划： | ||
| Lint-843. Digital Flip | ||
| 256. Paint House 序列型动态规划 | ||
| 265. Paint House II | ||
| 121. Best Time to Buy and Sell Stock | ||
| 122. Best Time to Buy and Sell Stock II | ||
| 123. Best Time to Buy and Sell Stock III | ||
| 188. Best Time to Buy and Sell Stock IV 还没做 | ||
| 309. Best Time to Buy and Sell Stock with Cooldown | ||
| 300. Longest Increasing Subsequence | ||
| 354. Russian Doll Envelopes 是300题的二维问题 | ||
| 划分型动态规划 | ||
| 279. Perfect Squares BFS剪枝用set | ||
| 132. Palindrome Partitioning II | ||
| Lint-437. Copy Books | ||
| 博弈型动态规划 | ||
| Lint-394. Coins in a Line | ||
| Lint-395. Coins in a Line II | ||
| Lint-396. Coins in a Line III | ||
| 背包型动态规划 --- 背包的总承重通常都需要放在状态里 | ||
| Lint-92. Backpack 可行性 | ||
| Lint-563. Backpack V 计数型 | ||
| Lint-564. Combination Sum IV 计数型 | ||
| Lint-125. Backpack II 最值型 | ||
| Lint-440. Backpack III 最值型 这一题可以一维数组把空间优化到极致，见视频讲解 | ||
| 416. Partition Equal Subset Sum | ||
| 区间型动态规划 | 取头 取尾 | |
| 516. Longest Palindromic Subsequence 在区间问题中，要按照区间长度的顺序计算 | ||
| 记忆化搜索，可以大大降低冗余。自上而下 | ||
| 5. Longest Palindromic Substring | ||
| 87. Scramble String | ||
| 312. Burst Balloons 消去型题目 | ||
| 双序列动态规划 | ||
| 1143. Longest Common Subsequence | ||
| 97. Interleaving String | ||
| 72. Edit Distance | ||
| 10. Regular Expression Matching | ||
| 474. Ones and Zeroes | ||
| 115. Distinct Subsequences | ||
| 44. Wildcard Matching 还没做 | ||
| 动态规划难题专场 | ||
| 221. Maximal Square | ||
| 639. Decode Ways II 还没做 | ||
| Lint-752. Rogue Knight Sven | ||
| Lint-971. Surplus Value Backpack 这道题不用掌握 | ||
| Lint-89. k Sum | ||
| 贪心算法 | ||
| 455. Assign Cookies | ||
| 435. Non-overlapping Intervals 其实是活动选择问题 | ||
| 位操作 | ||
| 29. Divide Two Integers | ||
| 191. Number of 1 Bits | ||
| 405. Convert a Number to Hexadecimal 不会 | ||
| 231. Power of Two | ||
| 268. Missing Number | ||
| 397. Integer Replacement 还没做 | ||
| 371. Sum of Two Integers | ||
| 172. Factorial Trailing Zeroes 还没做 | ||
| 260. Single Number III | ||
| 字符串 | ||
| 551. Student Attendance Record I | ||
| 760. Find Anagram Mappings | ||
| 5. Longest Palindromic Substring | ||
| 242. Valid Anagram | ||
| 796. Rotate String | ||
| 9. Palindrome Number 还没做 | ||
| 409. Longest Palindrome | ||
| 266. Palindrome Permutation | ||
| 267. Palindrome Permutation II | ||
| 516. Longest Palindromic Subsequence | ||
| 524. Longest Word in Dictionary through Deleting 还没做 | ||
| 392. Is Subsequence | ||
| 648. Replace Words 还没做 | ||
| 6. ZigZag Conversion | ||
| 8. String to Integer (atoi) | ||
| 12. Integer to Roman | ||
| 13. Roman to Integer | ||
| 14. Longest Common Prefix | ||
| 30. Substring with Concatenation of All Words | ||
| 248. Strobogrammatic Number III | ||
| 161. One Edit Distance | ||
| 前缀树 | ||
| 208. Implement Trie (Prefix Tree) | ||
| 211. Add and Search Word - Data structure design | ||
| 212. Word Search II 字典树 | ||
| 72. Edit Distance | ||
| Lint-623. K Edit Distance | ||
| 425. Word Squares | ||
| Question Numbers | ✨ Star ! | Second | Third | Forth | Fifth |
|---|---|---|---|---|---|
| 1-10 | |||||
| 11-20 | |||||
| 21-30 |
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