剑指offer_python：从上往下打印二叉树（数组存储结点）

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。

# -*- 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 []
        
        support = [root]
        ret = []
        
        while support:
            tmpNode = support[0]
            ret.append(tmpNode.val)
            
            if tmpNode.left:
                support.append(tmpNode.left)
            if tmpNode.right:
                support.append(tmpNode.right)
                
            del support[0]
            
        return ret