【LeetCode】107. Binary Tree Level Order Traversal II

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def levelOrderBottom(self, root):
        """
        :type root: TreeNode
        :rtype: List[List[int]]
        """
        re = []
        if not root:
            return re
        cur_level = [root]
        while cur_level:
            level_re = []
            next_level = []
            for temp in cur_level:
                level_re.append(temp.val)
                if temp.left:
                    next_level.append(temp.left)
                if temp.right:
                    next_level.append(temp.right)
            re.append(level_re)
            cur_level = next_level
        re.reverse()
        return re