HTMLify

from collections import deque

class Solution:
    def maxLevelSum(self, root: Optional[TreeNode]) -> int:
        if not root:
            return 0
        
        max_sum = float('-inf')
        ans = 1
        curr_level = 1
        queue = deque([root])
        
        while queue:
            level_sum = 0
            for _ in range(len(queue)):
                node = queue.popleft()
                level_sum += node.val
                
                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)
            
            if level_sum > max_sum:
                max_sum = level_sum
                ans = curr_level
            
            curr_level += 1
            
        return ans