📅  最后修改于: 2022-03-11 14:52:47.659000             🧑  作者: Mango
public int countNode(Node root){
//base case
if(root==null)
return 0;
//recursive call to left child and right child and
// add the result of these with 1 ( 1 for counting the root)
return 1 + countNode(root.left) + countNode(root.right);
}