翻译

给定一个二叉树，找出它的最大深度。

最大深度是指的从根节点一直到最远的叶节点中所有的节点数目。

原文

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.

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 dfs(TreeNode* root) {
        if (root == NULL)
            return 0;
        return 1 + max(dfs(root->left), dfs(root->right));
    }
    int maxDepth(TreeNode* root) {
        return dfs(root);
    }
};