515. 在每个树行中找最大值
Medium | Tree, Depth-First Search, Breadth-First Search, Binary Tree
Tree
530. 二叉搜索树的最小绝对差
Easy | Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree
538. 二叉搜索树转化为累加树
Medium | Tree, Depth-First Search, Binary Search Tree, Binary Tree
543. 二叉树的直径
Easy | Tree, Depth-First Search, Binary Tree
558. 二进制网格的逻辑或运算（四叉树表示）
Medium | Divide and Conquer, Tree
563. 二叉树的坡度
Easy | Tree, Depth-First Search, Binary Tree
572. 另一棵树的子树
Easy | Tree, Depth-First Search, String Matching, Binary Tree, Hash Function
589. N 叉树的前序遍历
Easy | Stack, Tree, Depth-First Search
590. N 叉树的后序遍历
Easy | Stack, Tree, Depth-First Search
606. 从二叉树构造字符串
Medium | String, Tree, Depth-First Search, Binary Tree