def hasPair(l1: List[Int], l2: List[Int], target: Int): Option[Pair[Int, Int]] = {
    val sortedList = (l1.toVector ++ l2.toVector).sorted

    var x = 0
    var y = sortedList.length - 1

    while (x < y) {
      if (sortedList(x) + sortedList(y) == target) {
        if ((l1.exists(_ == sortedList(x)) && l2.exists(_ == sortedList(y))) || (l2.exists(_ == sortedList(x)) && l1.exists(_ == sortedList(y))) ) {
        return Some(sortedList(y), sortedList(x))
        }
      } else if (sortedList(x) + sortedList(y) < target) {
        x = x + 1
      } else { // sum too big!
        y = y - 1
      }
    }

    return None
  }