python 按之字形順序打印二叉樹

'''
題目描述
請實現一個函數按照之字形打印二叉樹，
即第一行按照從左到右的順序打印，第二層按照從右至左的順序打印，第三行按照從左到右的順序打印，其他行以此類推。

層序遍歷的變種，噹噹前層是奇數層的時候，將出棧結果保存
噹噹前層是偶數層時，將出棧結果序列逆序保存
'''
# -*- coding:utf-8 -*-
class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None
class Solution:
    def Print(self, pRoot):
        # write code here
        if not pRoot.left and not pRoot.right:
            return pRoot.val
        stack1=[]
        stack1.append(pRoot)
        output=[]
        is_ou=False
        while(len(stack1)>0):
            print(type(stack1[0]),type(stack1))
            temp=[]
            temp_len=len(stack1)
            # print(temp_len)
            for i in range(temp_len):
                out_node=stack1.pop(0)
                # print(out_node.left,'hsihidsd')
                if out_node.left is not None:
                    stack1.append(out_node.left)
                if out_node.right is not None:
                    stack1.append(out_node.right)
                temp.append(out_node.val)
            # print(stack1)
            if not is_ou:
                output.extend(temp)
            else:
                output.extend(temp[::-1])
            is_ou=~is_ou

        return output

if __name__=='__main__':
    here=TreeNode(8)
    here.left=TreeNode(6)
    here.right=TreeNode(10)
    here.left.left=TreeNode(5)
    here.left.right = TreeNode(7)
    here.right.left = TreeNode(9)
    here.right.right = TreeNode(11)
    print(Solution().Print(here))
    # [8, 10, 6, 5, 7, 9, 11]