DFS：
LeetCode 51 N-Queens
LeetCode 37. Sudoku Solver
LeetCode 46. Permutations
LeetCode 47. Permutations II
LeetCode 39. Combination Sum
LeetCode 40. Combination Sum II
树:
LeetCode 145. Binary Tree Postorder Traversal (循环写法，复习一下直接抄即可)
LeetCode 105. Construct Binary Tree from Preorder and Inorder Traversal
LeetCode 102. Binary Tree Level Order Traversal
LeetCode 236. Lowest Common Ancestor of a Binary Tree
LeetCode 124. Binary Tree Maximum Path Sum
LeetCode 297. Serialize and Deserialize Binary Tree
dp：
LeetCode 121. Best Time to Buy and Sell Stock
LeetCode 122. Best Time to Buy and Sell Stock II
LeetCode 123. Best Time to Buy and Sell Stock III
LeetCode 188. Best Time to Buy and Sell Stock IV
LeetCode 139. Word Break
LeetCode 174. Dungeon Game
LeetCode 198. House Robber
LeetCode 213. House Robber II
LeetCode 322. Coin Change
LeetCode 1269. Number of Ways to Stay in the Same Place After Some Steps
二分：
LeetCode 33. Search in Rotated Sorted Array
LeetCode 74. Search a 2D Matrix
LeetCode 240. Search a 2D Matrix II
LeetCode 155. Min Stack
单调栈
LeetCode 84. Largest Rectangle in Histogram
LeetCode 496. Next Greater Element I
LeetCode 503. Next Greater Element II
单调队列
LeetCode 239. Sliding Window Maximum
其他经典题目：
LeetCode 31. Next Permutation
.etc