题解 | #从上往下打印二叉树#

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
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
        que = []
        ret = []
        if root is None:
            return
        que.append(root)
        
        while que:
            que_tmp = []
            for item in que:
                ret.append(item.val)
#                 print(item.val)
                if item.left:
                    que_tmp.append(item.left)
                if item.right:
                    que_tmp.append(item.right)
            que = que_tmp
#             print(que)
        return ret