二叉树的最大深度

/**
* Definition of TreeNode:
* class TreeNode {
* public:
* int val;
* TreeNode *left, *right;
* TreeNode(int val) {
* this->val = val;
* this->left = this->right = NULL;
* }
* }
*/
class Solution {
public:
　　/**
　　* @param root: The root of binary tree.
　　* @return: An integer
　　*/
　　int maxDepth(TreeNode *root) {
　　int lhight, rhight;
　　if (root == NULL) {
　　　　return 0;

　　}
　　lhight = maxDepth(root->left);
　　rhight = maxDepth(root->right);
　　if (lhight > rhight) {
　　　　return lhight+1;

　　}
　　else
　　　　return rhight+1;
　　}
};