Method setNPerm

app/src/main/java/cs/min2phase/Util.java:261–271

(int[] arr, int idx, int n)

    }

    static void setNPerm(int[] arr, int idx, int n) {
        arr[n - 1] = 0;
        for (int i = n - 2; i >= 0; i--) {
            arr[i] = idx % (n - i);
            idx /= (n - i);
            for (int j = i + 1; j < n; j++) {
                if (arr[j] >= arr[i])
                    arr[j]++;
            }
        }
    }

    static int getNPerm(int[] arr, int n) {
        int idx = 0;