问题描述

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.

问题分析

原来做过一题二叉树最小深度，这种题没有什么难度，直接递归就行了

代码实现

public int maxDepth(TreeNode root) {
        if (root == null) return 0;
        if (root.left == null && root.right == null) return 1;
        if (root.left == null) return maxDepth(root.right) + 1;
        if (root.right == null) return maxDepth(root.left) + 1;
        return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
    }