刷题日记:完全二叉树的节点个数

题目描述

题解

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var countNodes = function(root) {
    // 深度递归遍历二叉树即可,该题思路简单,不必多说直接上代码
    const dfs = function(root){
        if(!root) return
        num += 1
        dfs(root.left)
        dfs(root.right)
    } 
    let num = 0
    dfs(root)
    return num
};