Covid sampling Codechef

    private static int[][][] fr = new int[61][61][2];
    private static int[][][] condFr = new int[61][121][2];

    private static void preprocess(int n, int p) {
        Random random = new Random();
        for (int attempt = 0; attempt < 100000; attempt++) {
            realGrid = new int[n][n];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    if (random.nextDouble() < p * 0.01) {
                        realGrid[i][j] = 1;
                    }
                }
            }
            int[] sumR = new int[n];
            for (int row = 0; row < n; row++) {
                sumR[row] = realGrid[row][0];
                for (int c = 1; c < n; c++) {
                    sumR[row] += realGrid[row][c];
                }
            }
            int[] sumC = new int[n];
            for (int col = 0; col < n; col++) {
                sumC[col] = realGrid[0][col];
                for (int r = 1; r < n; r++) {
                    sumC[col] += realGrid[r][col];
                }
            }
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    int sum = 0;
                    for (int x = i; x < n; x++) {
                        sum += realGrid[x][j];
                    }
                    for (int y = j; y < n; y++) {
                        sum += realGrid[i][y];
                    }
                    if (realGrid[i][j] == 1) {
                        fr[sumR[i]][sumC[j]][1]++;
                        condFr[sum][2 * n - i - j][1]++;
                    } else {
                        fr[sumR[i]][sumC[j]][0]++;
                        condFr[sum][2 * n - i - j][0]++;
                    }
                }
            }
        }

        double sumAll = 0;
        double sumPairs = 0;
        for (int i = 0; i < 61; i++) {
            for (int j = 0; j < 61; j++) {
                sumPairs += fr[i][j][0] + fr[i][j][1];
            }
        }

        for (int i = 0; i < 61; i++) {
            for (int j = 0; j < 61; j++) {
                double prob = (fr[i][j][0] + fr[i][j][1] + .0) / sumPairs;
                if (fr[i][j][0] + fr[i][j][1] > 0) {
                    double p0 = (1.0 * fr[i][j][0]) / (fr[i][j][0] + fr[i][j][1]);
                    double p1 = 1 - p0;
//                    System.out.println("i = " + i + ", j = " + j + ", prob  = " +
//                            df.format(prob) + ", 0 -> " + p0 + ", 1 -> " + p1);
                }
            }
        }
    }