scope intersectSortedIntArrays.

// may return null when result is empty

static int[] intersectSortedIntArrays(int[] a, int[] b, IntBuffer buf default null) {

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

  // swap if a is longer than b

  if (la > lb) {

    int[] temp = a; a = b; b = temp;

    int temp2 = la; la = lb; lb = temp2;

  }

  // special case zero elements

  if (la == 0) null;

  // special case one element

  if (la == 1)

    ret Arrays.binarySearch(b, a[0]) >= 0 ? a : null;

  if (buf == null) buf = new IntBuffer; else buf.reset();

  recurse(a, b, buf, 0, la, 0, lb);

  ret buf.toArray();

}

svoid #recurse(int[] a, int[] b, IntBuffer buf, int aFrom, int aTo, int bFrom, int bTo) {

  if (aFrom >= aTo || bFrom >= bTo) ret; // nothing to do

  // start in the middle of a, search this element in b

  int i = (aFrom+aTo)/2;

  int x = a[i];

  int j = Arrays.binarySearch(b, bFrom, bTo, x);

  if (j >= 0) {

    // element found

    recurse(a, b, buf, aFrom, i, bFrom, j);

    buf.add(x);

    recurse(a, b, buf, i+1, aTo, j+1, bTo);

  } else {

    j = -j-1;

    recurse(a, b, buf, aFrom, i, bFrom, j);

    recurse(a, b, buf, i+1, aTo, j, bTo);

  }

}

end scope