weixin_43876597的博客

记忆化搜索，使用数组，记录val的最少硬币数量；递归加bfs;

Leetcode 314. Binary Tree Vertical Order Traversal Approach 2: BFS without Sorting class Solution { public List<List<Integer>> verticalOrder(TreeNode root) { List<List<Integer>> output = new ArrayList(); if (root == null)

Leetcode 742. Closest Leaf in a Binary Tree Approach #1: Convert to Graph 把树转换为以k节点为中心的图，从k节点开始层序遍历，返回最先遇到的叶子结点。 class Solution { public int findClosestLeaf(TreeNode root, int k) { Map<TreeNode, List<TreeNode>> graph = new HashMap()