// is allowed to return null when result is empty

static int[] intersectSortedIntArrays_ofs(int[] a, int[] b, int ofs) {

  int i = 0, j = 0, la = l(a), lb = l(b);

  if (la == 0 || lb == 0) null;

  IntBuffer buf = new(min(la, lb));

  while (i < la && j < lb) {

    int x = a[i], y = b[j]+ofs;

    if (x == y) {

      buf.add(x);

      ++i;

      ++j;

    } else if (x < y)

      ++i;

    else

      ++j;

  }

  ret buf.toArray();

}