leetcode 第104题 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.

思路：递归实现。代码易懂。

C++实现如下：

/** * 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;        if(root->left == NULL && root->right == NULL)            return 1;        else            return max(maxDepth(root->left),maxDepth(root->right)) + 1;    }};