/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
 *
 * 
 * @param root TreeNode类 
 * @return int整型
 */
int maxDepth(struct TreeNode* root ) {
    // write code here
    if(root==NULL)
   {
       return 0;
   }
    int x = maxDepth(root->left)+1;
    int y = maxDepth(root->right)+1;
    return (x>y)?x:y;
}