P16.scala

  def drop[T](n: Int, ts: Seq[T]): Seq[T] =
    ts.foldLeft((n, Seq[T]()))((acc, t) => {
      val (x, ts) = acc
      if (x == 1) (n, ts) else (x - 1, ts :+ t)
    })._2

  def p16[T](nr: Int, list: Seq[T]): Seq[T] = {
    def p16( list: Seq[T], index: Int, acc: Seq[T]): Seq[T] = list match {
      case Nil => acc
      case h :: t if (nr == index) =>  p16( t, 1, acc)
      case h :: t =>  p16( t, index + 1, acc :+ h)
    }
    p16( list, 1, Nil)
  }