[Python] Simple and fast recursive solution
\nfrom collections import defaultdict\n\nclass Solution:\n    def maxLevelSum(self, root: TreeNode) -> int:\n        levels = defaultdict(int)\n        def sum_
```\nfrom collections import defaultdict\n\nclass Solution:\n    def maxLevelSum(self, root: TreeNode) -> int:\n        levels = defaultdict(int)\n        def sum_vals(root, depth):\n            if root:\n                levels[depth] += root.val\n                sum_vals(root.left,  depth+1)\n                sum_vals(root.right, depth+1)\n\t\t\t\n        sum_vals(root, 1)\n        return max(levels, key=levels.get)\n```\n\nSimply find the sum for each level by recursing into each child with that childs level, and then return the level with the highest sum.
['Recursion', 'Python', 'Python3']