Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3
/ 9 20
/ 15 7
return its depth = 3.
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public boolean isBalanced(TreeNode root) { if(root == null) return true; int l = depth(root.left); int r = depth(root.right); return Math.abs(l - r) < 2 && isBalanced(root.left) && isBalanced(root.right); } public int depth(TreeNode root){ if(root == null) return 0; return Math.max(depth(root.left), depth(root.right)) + 1; } }
在maxDepth of BST的基础上进一步做文章。
原文：https://www.cnblogs.com/wentiliangkaihua/p/11432879.html