102. Binary Tree Level Order Traversal - LeetCode

from functools import reduce


# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def levelOrder(self, root) -> list[list[int]]:
        result, q = [], [root]
        while True:
            q = [x for x in q if x]
            v = [x.val for x in q]
            if not v:
                break
            result.append(v)
            q = reduce(lambda a, b: a + [b.left, b.right], q, [])
        return result