[Python] Clean BFS solution with deque
\ndef maxLevelSum(self, root: Optional[TreeNode]) -> int:\n        \n        q = deque([(root,1)])\n        \n        max_sum = -float(\'inf\')\n        \n     
```\ndef maxLevelSum(self, root: Optional[TreeNode]) -> int:\n        \n        q = deque([(root,1)])\n        \n        max_sum = -float(\'inf\')\n        \n        while q:\n            \n            level_sum = 0\n            \n            for _ in range(len(q)):\n                cur, level = q.popleft()\n                \n                level_sum += cur.val\n                \n                if cur.left:\n                    q.append((cur.left,level+1))\n                if cur.right:\n                    q.append((cur.right,level+1))\n            \n            if level_sum > max_sum:\n                    max_sum, min_level = level_sum, level\n                \n        return min_level\n```
['Breadth-First Search', 'Queue', 'Python']