题解 | #从下到上打印二叉树#

# 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 root TreeNode类 
# @return int整型二维数组
#
from collections import deque

class Solution:
    def levelOrderBottom(self , root: TreeNode) -> List[List[int]]:
        if not root:
            return []
        result = []
        q = deque()
        q.append(root)
        while q:
            count = len(q)
            tmp = []
            for _ in range(count):
                node = q.popleft()
                tmp.append(node.val)
                if node.left:
                    q.append(node.left)
                if node.right:
                    q.append(node.right)
            result.append(tmp)
        result.reverse()
        return result

        # write code here