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