Method getNParity

app/src/main/java/cs/min2phase/Util.java:252–259

(int idx, int n)

    }

    static int getNParity(int idx, int n) {
        int p = 0;
        for (int i = n - 2; i >= 0; i--) {
            p ^= idx % (n - i);
            idx /= (n - i);
        }
        return p & 1;
    }

    static void setNPerm(int[] arr, int idx, int n) {
        arr[n - 1] = 0;