docs: public static int intersectionSize(long[] x, long[] y) {
      final int lx = x.length, ly = y.length;
      final int min = (lx < ly) ? lx : ly;
      int res = 0;
      for(int i = 0; i < min; i++) {
        res += Long.bitCount(x[i] & y[i]);
      }
      return res;
    }