剑指offer——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
        if root ==None :
            return []
        res,queue=[],[root]
        while queue:
            tmp=queue.pop(0)
            res.append(tmp.val)
            if tmp.left:
                queue.append(tmp.left)
            if tmp.right:
                queue.append(tmp.right)
        return res