quick code for http://stackoverflow.com/q/19645961/298389

decode.scala

def decode[A](xs: List[(Int, A)]) : Seq[A] = xs match {
  case Nil => Nil
  case (times, code) :: xs => (for (i <- 1 to times) yield code) ::: decode(xs)
}

// you may also replace
//    (for (i <- 1 to times) yield code)
// with
//    Seq.fill(3)(code)
// so you will get 
//    case (times, code) :: xs => Seq.fill(times)(code) ::: decode(xs)