melb scala ranges challenge

gistfile1.scala

def ranges(ints: Seq[Int]): Seq[(Int, Int)] = {
    ints.sorted.foldLeft( Seq[(Int,Int)]() )(
        (acc: Seq[(Int,Int)], n: Int) => acc match {
            // case Nil => acc :+ (n,n)
            case x :: (a,z) if (z == n) => acc
            case x :: (a,z) if (z+1 == n) => x :+ (a, n)
            case _ => acc :+ (n,n)
        }   
    )   
}