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 )           return 0;                    int left  = TreeDepth(pRoot->left);           int right = TreeDepth(pRoot->right);           return left > right ? ( left + 1 ) : ( right + 1 );    }};