[LeetCode]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.

注意对于root为NULL时返回0。代码如下：

/** * Definition for binary tree * 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;}        int leftdepth = maxDepth(root->left);    int rightdepth = maxDepth(root->right);    int maxdepth = max(leftdepth,rightdepth)+1;    return maxdepth;    }};