Method getNPerm

app/src/main/java/cs/min2phase/Util.java:273–284

(int[] arr, int n)

    }

    static int getNPerm(int[] arr, int n) {
        int idx = 0;
        for (int i = 0; i < n; i++) {
            idx *= (n - i);
            for (int j = i + 1; j < n; j++) {
                if (arr[j] < arr[i]) {
                    idx++;
                }
            }
        }
        return idx;
    }

    static int getComb(int[] arr, int mask) {
        int end = arr.length - 1;