截止至今LeetCode题目总量已经有1582题，估计将来每年平均增长300题左右，大部分人肯定是刷不完的，所以得有选择地刷LeetCode。
一种公认的刷题策略是按类别刷题，可是每个类别也有许多题，在有限的时间里到底该刷哪些题呢？个人根据LeetCode官方给出的每个题目的出现频率，整理并收录了每个类别里高频出现的题目，对于官方统计频率太低的题目，不予收录，最终得到了这个高频题目表格。
例如，对于下图中题号#275与#270的题目将被收录，并且#275出现频率大于#270；而对于题号#1011与#1182的题目，因为出现频率太低，将不被收录：
撸起键盘加油干！祝大家成功上岸！整理不易，点个赞吧！
深度优先遍历篇-69题(Depth-first Search, 69 problems)
2020/03/29更新： 之前有些题目的跳转链接不对，现在已经改过来了
数据日期： 2020/03/26 (此时LeetCode题目数量：1582)
数据来源： LeetCode官方，将不同类别的题目按照官方给的出现频率(Frequency)降序排列，取有频率统计的题。
| 排序 | 题号 | 题目 | 通过率 | 难度 |
|---|---|---|---|---|
| 1 | #679 | 24 Game | 0.424 | 困难 |
| 2 | #104 | Maximum Depth of Binary Tree | 0.726 | 简单 |
| 3 | #108 | Convert Sorted Array to Binary Search Tree | 0.699 | 简单 |
| 4 | #546 | Remove Boxes | 0.496 | 困难 |
| 5 | #394 | Decode String | 0.493 | 中等 |
| 6 | #114 | Flatten Binary Tree to Linked List | 0.681 | 中等 |
| 7 | #105 | Construct Binary Tree from Preorder and Inorder Traversal | 0.646 | 中等 |
| 8 | #488 | Zuma Game | 0.406 | 困难 |
| 9 | #101 | Symmetric Tree | 0.506 | 简单 |
| 10 | #109 | Convert Sorted List to Binary Search Tree | 0.711 | 中等 |
| 11 | #542 | 01 Matrix | 0.381 | 中等 |
| 12 | #199 | Binary Tree Right Side View | 0.639 | 中等 |
| 13 | #491 | Increasing Subsequences | 0.463 | 中等 |
| 14 | #200 | Number of Islands | 0.478 | 中等 |
| 15 | #257 | Binary Tree Paths | 0.63 | 简单 |
| 16 | #301 | Remove Invalid Parentheses | 0.452 | 困难 |
| 17 | #124 | Binary Tree Maximum Path Sum | 0.397 | 困难 |
| 18 | #695 | Max Area of Island | 0.632 | 中等 |
| 19 | #112 | Path Sum | 0.493 | 简单 |
| 20 | #638 | Shopping Offers | 0.571 | 中等 |
| 21 | #664 | Strange Printer | 0.43 | 困难 |
| 22 | #690 | Employee Importance | 0.575 | 简单 |
| 23 | #207 | Course Schedule | 0.496 | 中等 |
| 24 | #100 | Same Tree | 0.569 | 简单 |
| 25 | #133 | Clone Graph | 0.525 | 中等 |
| 26 | #111 | Minimum Depth of Binary Tree | 0.418 | 简单 |
| 27 | #329 | Longest Increasing Path in a Matrix | 0.401 | 困难 |
| 28 | #130 | Surrounded Regions | 0.398 | 中等 |
| 29 | #337 | House Robber III | 0.564 | 中等 |
| 30 | #110 | Balanced Binary Tree | 0.509 | 简单 |
| 31 | #99 | Recover Binary Search Tree | 0.559 | 困难 |
| 32 | #863 | All Nodes Distance K in Binary Tree | 0.477 | 中等 |
| 33 | #332 | Reconstruct Itinerary | 0.363 | 中等 |
| 34 | #515 | Find Largest Value in Each Tree Row | 0.585 | 中等 |
| 35 | #547 | Friend Circles | 0.557 | 中等 |
| 36 | #733 | Flood Fill | 0.53 | 简单 |
| 37 | #513 | Find Bottom Left Tree Value | 0.688 | 中等 |
| 38 | #721 | Accounts Merge | 0.323 | 中等 |
| 39 | #113 | Path Sum II | 0.589 | 中等 |
| 40 | #106 | Construct Binary Tree from Inorder and Postorder Traversal | 0.675 | 中等 |
| 41 | #514 | Freedom Trail | 0.38 | 困难 |
| 42 | #529 | Minesweeper | 0.594 | 中等 |
| 43 | #473 | Matchsticks to Square | 0.371 | 中等 |
| 44 | #417 | Pacific Atlantic Water Flow | 0.408 | 中等 |
| 45 | #494 | Target Sum | 0.441 | 中等 |
| 46 | #129 | Sum Root to Leaf Numbers | 0.624 | 中等 |
| 47 | #98 | Validate Binary Search Tree | 0.295 | 中等 |
| 48 | #971 | Flip Binary Tree To Match Preorder Traversal | 0.43 | 中等 |
| 49 | #210 | Course Schedule II | 0.465 | 中等 |
| 50 | #576 | Out of Boundary Paths | 0.36 | 中等 |
| 51 | #711 | Number of Distinct Islands II | 0.561 | 困难 |
| 52 | #685 | Redundant Connection II | 0.335 | 困难 |
| 53 | #472 | Concatenated Words | 0.438 | 困难 |
| 54 | #1254 | Number of Closed Islands | 0.589 | 中等 |
| 55 | #339 | Nested List Weight Sum | 0.777 | 简单 |
| 56 | #116 | Populating Next Right Pointers in Each Node | 0.564 | 中等 |
| 57 | #439 | Ternary Expression Parser | 0.548 | 中等 |
| 58 | #505 | The Maze II | 0.439 | 中等 |
| 59 | #490 | The Maze | 0.442 | 中等 |
| 60 | #117 | Populating Next Right Pointers in Each Node II | 0.464 | 中等 |
| 61 | #694 | Number of Distinct Islands | 0.457 | 中等 |
| 62 | #323 | Number of Connected Components in an Undirected Graph | 0.553 | 中等 |
| 63 | #499 | The Maze III | 0.303 | 困难 |
| 64 | #261 | Graph Valid Tree | 0.449 | 中等 |
| 65 | #737 | Sentence Similarity II | 0.41 | 中等 |
| 66 | #533 | Lonely Pixel II | 0.454 | 中等 |
| 67 | #366 | Find Leaves of Binary Tree | 0.73 | 中等 |
| 68 | #364 | Nested List Weight Sum II | 0.687 | 中等 |
| 69 | #531 | Lonely Pixel I | 0.651 | 中等 |
相关/参考链接
leetcode-cn
leetcode