def lcsRec[T]: (IndexedSeq[T], IndexedSeq[T]) => IndexedSeq[T] = {
    case (a +: as, b +: bs) if a == b => a +: lcsRec(as, bs)
    case (as, bs) if as.isEmpty || bs.isEmpty => IndexedSeq[T]()
    case (a +: as, b +: bs) =>
      val (s1, s2) = (lcsRec(a +: as, bs), lcsRec(as, b +: bs))
      if(s1.length > s2.length) s1 else s2
  }