题解 | #完全二叉树结点数#

using System;
using System.Collections.Generic;

/*
public class TreeNode
{
    public int val;
    public TreeNode left;
    public TreeNode right;

    public TreeNode (int x)
    {
        val = x;
    }
}
*/

class Solution {
    /**
     * 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 head TreeNode类
     * @return int整型
     */
    public int nodeNum (TreeNode head) {
        // write code here
        int nCount = 0;
        if (head == null)
            return nCount;
        nCount++;
        return nCount + nodeNum(head.left) + nodeNum(head.right);
    }
}