题目来源：https://leetcode.com/problems/maximum-depth-of-binary-tree/

问题描述

104. Maximum Depth of Binary Tree

Easy

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.

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题意

求二叉树的最大深度。

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思路

递归

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代码

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public int maxDepth(TreeNode root) { if (root == null) { return 0; } return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1; } }