1161. Maximum Level Sum of a Binary Tree

https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree

Python

from collections import defaultdict


class Solution:
    def maxLevelSum(self, root: Optional[TreeNode]) -> int:
        mapper = defaultdict(int)

        def dfs(node, level):
            if not node:
                return
            
            mapper[level] += node.val

            dfs(node.left, level+1)
            dfs(node.right, level+1)
        
        dfs(root, 1)

        reverse_map = defaultdict(list)
        for key, value in mapper.items():
            reverse_map[value].append(key)
        
        return min(reverse_map[max(mapper.values())])