LeetCode: 104. Maximum Depth of Binary Tree

题目描述

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.

**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.

解题思路 —— 递归求解

二叉树的最大高度等于其左子树的最大高度和右子树的最大高度的最大值加一。

AC 代码

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */
class Solution {
public:
    int maxDepth(TreeNode* root) {
        if(root == nullptr) return 0;
        //左子树的最大高度和右子树的最大高度的最大值加一
        return max(maxDepth(root->left), maxDepth(root->right)) + 1;
    }
};