p15.scala

object S99_P15 {
  def duplicateN[T](n: Int, ts: Seq[T]): Seq[T] =
    ts flatMap { List.fill(n)(_) }

  
  def duplicateN[T](n: Int, ts: Seq[T]): Seq[T] = ts match{
  	case Nil => Nil
  	case head::tail => List.fill(n)(head) ++ duplicateN(n,tail)
  }  

  def duplicateN[T](n: Int, ts: Seq[T]): Seq[T] = {
    def go(ts: Seq[T], acc: Seq[T]): Seq[T] = ts match {
      case Nil => acc
      case head :: tail => go(tail, acc ++ List.fill(n)(head))
    }
    go(ts, Seq())
  }
}