【LeetCode & 剑指offer刷题】树题4：104 Maximum Depth of Binary Tree

【LeetCode & 剑指offer 刷题笔记】目录（持续更新中...）

104. Maximum Depth of Binary Tree

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.

 * 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 == NULL) return 0; //递归的出口

        int depth_left = maxDepth(root->left); //用递归的方法，左子树的深度

        int depth_right = maxDepth(root->right); //右子树的深度

       

        return 1 + max(depth_left, depth_right);

       

    }

};