public int compare(int i, int j) { return (int)(a[i] - a[j]); }
public int compare(int i, int j) { double vi = a[i]; double vj = a[j]; return (vi == vj) ? 0 : (vi > vj) ? 1 : -1; }
        public int compare(int i, int j) { return (int)(a[i] - a[j]); }