题解 | #按之字形顺序打印二叉树#

import re

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
#
# @param pRoot TreeNode类
# @return int整型二维数组
#
from collections import deque


class Solution:
    def Print(self, pRoot: TreeNode) -> List[List[int]]:
        # write code here
        if pRoot == None:
            return []

        queue = deque()
        layer = 0
        queue.append(pRoot)
        l=[]

        while len(queue) != 0:
            size = len(queue)
            row = []
            
            for i in range(size):
                if layer % 2 == 0:  # 顺序
                    curr = queue.popleft()
                    row.append(curr.val)
                    
                    if curr.left:
                        queue.append(curr.left)
                    if curr.right:
                        queue.append(curr.right)

                else: # 倒叙
                    curr = queue.pop()
                    row.append(curr.val)
                    # print(row)
                    if curr.right:
                        queue.appendleft(curr.right)
                    if curr.left:
                        queue.appendleft(curr.left)
                   

            
            
            l.append(row)
            layer +=1
        
        return l

注意appendleft，pop，popleft函数结合使用

reverse(quene)，len(queue)、copy.copy(d)、copy.deepcopy(d)都可以用