59.按之字形顺序打印二叉树(python)

题目描述

请实现一个函数按照之字形打印二叉树，即第一行按照从左到右的顺序打印，第二层按照从右至左的顺序打印，第三行按照从左到右的顺序打印，其他行以此类推。

# -*- 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 pRoot == None:
            return []
        stack1=[pRoot]
        stack2=[]
        ret=[]
        while stack1 or stack2:
            if stack1:
                tmpRet = []
                while stack1:
                    tmpNode = stack1.pop()
                    tmpRet.append(tmpNode.val)
                    if tmpNode.left:
                        stack2.append(tmpNode.left)
                    if tmpNode.right:
                        stack2.append(tmpNode.right)
                ret.append(tmpRet)
            if stack2:
                tmpRet=[]
                while stack2:
                    tmpNode = stack2.pop()
                    tmpRet.append(tmpNode.val)
                    if tmpNode.right:
                        stack1.append(tmpNode.right)
                    if tmpNode.left:
                        stack1.append(tmpNode.left)
                ret.append(tmpRet)
        return ret

2020-01-01 17:39:12