519. 随机翻转矩阵

import random
from typing import List


class Solution:

    def __init__(self, m: int, n: int):
        self.ones = set()
        self.shape = (m, n)

    def flip(self) -> List[int]:
        m, n = self.shape
        p = -1
        while p < 0 or p in self.ones:
            p = random.randint(0, m * n - 1)
        self.ones.add(p)

        return [p // n, p % n]

    def reset(self) -> None:
        self.ones = set()