Easy solution
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity: o(n)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity: o(n)\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\nclass Solution:\n\n    def __init__(self, m: int, n: int):\n        self.ROW = m\n        self.COL = n\n        self.cac = set()\n\n    def flip(self) -> List[int]:\n        i = random.randint(0, self.ROW - 1)\n        j = random.randint(0, self.COL - 1)\n        while (i, j) in self.cac:\n            i = random.randint(0, self.ROW - 1)\n            j = random.randint(0, self.COL - 1)\n        self.cac.add((i, j))\n        return [i, j]\n\n    def reset(self) -> None:\n        self.cac.clear()\n\n\n# Your Solution object will be instantiated and called as such:\n# obj = Solution(m, n)\n# param_1 = obj.flip()\n# obj.reset()\n```
['Python3']