515. Find Largest Value in Each Tree Row - LeetCode

from typing import Optional


# 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 Solution1:
    def largestValues(self, root: Optional[TreeNode]) -> list[int]:
        result, nodes = [], [x for x in [root] if x]
        while nodes:
            result.append(max(x.val for x in nodes))
            _next = []
            _next.extend([x.left for x in nodes if x.left])
            _next.extend([x.right for x in nodes if x.right])
            nodes = _next
        return result


class Solution:
    # https://leetcode.com/problems/find-largest-value-in-each-tree-row/solutions/99000/python-bfs/
    def largestValues(self, root: Optional[TreeNode]) -> list[int]:
        result, nodes = [], [root]
        while any(nodes):
            result.append(max(x.val for x in nodes))
            nodes = [x for n in nodes for x in [n.left, n.right] if x]
        return result