题解 | #按之字形顺序打印二叉树#

# 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
#
class Solution:
    def Print(self , pRoot: TreeNode) -> List[List[int]]:
        res = []
        remain = []
        if not pRoot:
            return []
        if pRoot:
            remain.append(pRoot)
        k = 1
        while remain:
            n = len(remain)
            tmp = []
            stack = []
            for i in range(n):
                node = remain.pop(0)
                tmp.append(node.val)
                stack.append(node)
            
            while stack:
                node = stack.pop()
                if k % 2 == 0:
                    if node.left:
                        remain.append(node.left)
                    if node.right:
                        remain.append(node.right)
                else:
                    if node.right:
                        remain.append(node.right)
                    if node.left:
                        remain.append(node.left)
            res.append(tmp)
            k += 1
        return res
        # write code here