[Python3] enumeration
Please pull this commit for solutions of biweekly 86. \n\n\nclass Solution:\n    def maximumRows(self, mat: List[List[int]], cols: int) -> int:\n        m, n = 
Please pull this [commit](https://github.com/gaosanyong/leetcode/commit/35b262c16bc702edbad6adc895bc8321a037ebaa) for solutions of biweekly 86. \n\n```\nclass Solution:\n    def maximumRows(self, mat: List[List[int]], cols: int) -> int:\n        m, n = len(mat), len(mat[0])\n        masks = []\n        for i in range(m): \n            mask = reduce(xor, (1<<j for j in range(n) if mat[i][j]), 0)\n            masks.append(mask)\n        ans = 0 \n        for x in range(1<<n): \n            if x.bit_count() <= cols: \n                ans = max(ans, sum(mask & x == mask for mask in masks))\n        return ans \n```
['Python3']