大数据中二叉树的层序遍历是怎样的

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题目描述

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题解

# Definition for a binary tree node.# class TreeNode:#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution:    def levelOrderBottom(self, root: TreeNode) -> List[List[int]]:        if not root:            return []        result = []        level = [root]        while len(level)>0:            tmp1=[]            res = []            for node in level:                if node.left:                    tmp1.append(node.left)                if node.right:                    tmp1.append(node.right)                res.append(node.val)            level = tmp1            result.append(res)        # 就输出这变下就可以了        return result[::-1]