题目描述

从上往下打印出二叉树的每个节点，同层节点从左至右打印。

class Solution:    # 返回从上到下每个节点值列表，例：[1,2,3]    def PrintFromTopToBottom(self, root):        # write code here        queen=[]        res=[]        if root is not None:            queen.append(root)            while len(queen) is not 0:                temp=queen.pop(0)                res.append(temp.val)                if temp.left is not None:                    queen.append(temp.left)                if temp.right is not None:                    queen.append(temp.right)        return res