题解 | #按之字形顺序打印二叉树#

#     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]]:
        # write code here
        left2right = True
        list2root = [pRoot]
        if not pRoot:
            return None
        result = []
        result.append([list2root[0].val])
        while list2root:  # 因为这里是从第二层开始遍历的，所以别忘了在上面把跟节点的值加上
            temp  = []
            temp2 = []
            for ele in list2root:
                if ele.left:
                    temp.append(ele.left)
                    temp2.append(ele.left.val)
                if ele.right:
                    temp.append(ele.right)
                    temp2.append(ele.right.val)
            list2root = temp
            if list2root:  # 如本层有节点才添加到result列表里，否则就多添加了一层空列表
                left2right = not left2right
                if left2right:
                    result.append(temp2)
                else:
                    result.append(temp2[::-1])
        return result