求二叉树的深度

/*struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}};*/class Solution {public:    int TreeDepth(TreeNode* pRoot)    {        if(pRoot==NULL)            return 0;        int m = TreeDepth(pRoot->left);        int n = TreeDepth(pRoot->right);        return 1+(m>n?m:n);                        }};