1.dfs
https://leetcode-cn.com/problems/letter-combinations-of-a-phone-number/
2022.3.29 9 路径总和 https://leetcode-cn.com/problems/path-sum/
2022.3.29 9 路径总和2 https://leetcode-cn.com/problems/path-sum-ii/
2022.3.29 7 根节点到叶节点数字之和 https://leetcode-cn.com/problems/sum-root-to-leaf-numbers/
2022.3.29 6 二叉树展开为链表 https://leetcode-cn.com/problems/flatten-binary-tree-to-linked-list/
2022.3.30 9 二叉树中的最大路径和 https://leetcode-cn.com/problems/binary-tree-maximum-path-sum
2022.4.19 9 周赛.相邻字符不同的最长路径 https://leetcode-cn.com/problems/longest-path-with-different-adjacent-characters/
2022.3.30 6 二叉树的最小深度 https://leetcode-cn.com/problems/minimum-depth-of-binary-tree
2022.3.31 7 克隆图 https://leetcode-cn.com/problems/clone-graph/
2022.4.13 7 剑指12.矩阵中的路径 https://leetcode-cn.com/problems/ju-zhen-zhong-de-lu-jing-lcof/
2022.4.21 9 剑指26.树的子结构 https://leetcode-cn.com/problems/shu-de-zi-jie-gou-lcof/
2022.4.22 8 剑指28.对称的二叉树 https://leetcode-cn.com/problems/dui-cheng-de-er-cha-shu-lcof/
2022.4.26 9 中兴捧月.24点游戏 https://leetcode-cn.com/problems/24-game/
2022.4.27 6 剑指33.二叉搜索树的后序遍历序列 https://leetcode-cn.com/problems/er-cha-sou-suo-shu-de-hou-xu-bian-li-xu-lie-lcof/
2022.4.28 9 剑指36.二叉搜索树与双向链表 https://leetcode-cn.com/problems/er-cha-sou-suo-shu-yu-shuang-xiang-lian-biao-lcof/
2022.4.29 9 剑指38.字符串的排列 https://leetcode-cn.com/problems/zi-fu-chuan-de-pai-lie-lcof/
2022.4.29 8 剑指37.序列化二叉树 https://leetcode-cn.com/problems/xu-lie-hua-er-cha-shu-lcof/
2022.5.27 8 剑指68 二叉树的最近公共祖先 https://leetcode.cn/problems/er-cha-shu-de-zui-jin-gong-gong-zu-xian-lcof/
2022.6.28 7 22.括号生成 https://leetcode.cn/problems/generate-parentheses/
2022.9.25 8 311周赛.反转二叉树的奇数层 https://leetcode.cn/problems/reverse-odd-levels-of-binary-tree/

(1) flood-fill 算法
2022.3.31 9 被围绕的区域 https://leetcode-cn.com/problems/surrounded-regions/
2022.4.1 9 岛屿数量 https://leetcode-cn.com/problems/number-of-islands/

(2) 拓扑排序
2022.4.1 9 课程表II https://leetcode-cn.com/problems/course-schedule-ii/
2022.9.2 9 308周赛 https://leetcode.cn/problems/build-a-matrix-with-conditions/

(3)dfs/bfs解连通图中点的个数
2022.7.1 2316. 统计无向图中无法互相到达点对数 https://leetcode.cn/problems/count-unreachable-pairs-of-nodes-in-an-undirected-graph/
2022.7.4 9 299周赛.从树中删除边的最小分数 https://leetcode.cn/problems/minimum-score-after-removals-on-a-tree/