301. 移除无效的括号
Hard | String, Backtracking, Breadth-First Search
Backtracking
39. 组合总和
Medium | Array, Backtracking
40. 组合总和 II
Medium | Array, Backtracking
46. 全排列
Medium | Array, Backtracking
47. 全排列 II
Medium | Array, Backtracking, Sorting
51. N皇后
Hard | Array, Backtracking
52. N 皇后 II
Hard | Backtracking
77. 组合
Medium | Backtracking
78. 子集
Medium | Array, Backtracking, Bit Manipulation
79. 单词搜索
Medium | Array, String, Backtracking, Depth-First Search, Matrix
89. 格雷编码
Medium | Math, Backtracking, Bit Manipulation
93. 复原 IP 地址
Medium | String, Backtracking
95. 不同的二叉搜索树 II
Medium | Dynamic Programming, Backtracking, Tree, Binary Search Tree, Binary Tree