求二叉树第K层的节点个数

int GetNodeNumKthLevel(BinaryTree *pRoot, int k )
{
if (pRoot == NULL || k < 1)
return 0;
if (k == 1)
return 1;
int numLeft = GetNodeNumKthLevel(pRoot->lchild, k - 1);
int numRight = GetNodeNumKthLevel(pRoot->rchild, k - 1);
return (numLeft + numRight);
}