随机翻转矩阵

/*
 * This implementation of the Solution class uses Java Streams to help with array manipulation.
 * It initializes the object with the given dimensions m and n.
 * The flip method returns a random index (i, j) where matrix[i][j] == 0 and sets matrix[i][j] = 1.
 * The reset method sets all the values of the matrix to 0.
 */
import java.util.*;
import java.util.stream.*;

class Solution {
    private int m, n, total;
    private Map<Integer, Integer> map;
    private Random rand;

    public Solution(int m, int n) {
        this.m = m;
        this.n = n;
        this.total = m * n;
        this.map = new HashMap<>();
        this.rand = new Random();
    }

    public int[] flip() {
        int r = rand.nextInt(total--);
        int x = map.getOrDefault(r, r);
        map.put(r, map.getOrDefault(total, total));
        return Stream.of(x).map(i -> new int[]{i / n, i % n}).findFirst().get();
    }

    public void reset() {
        map.clear();
        total = m * n;
    }
}