Scalaで素数

prime.scala

object Main extends App{
    import java.{util => ju}
    import scala.annotation._
    import scala.collection._
    import scala.collection.{mutable => mu}
    import scala.collection.JavaConverters._
    import scala.math._
    
    val sc = new ju.Scanner(System.in)

    /* code here */
    def primemain(primelist:List[Int], remain:List[Int], limit:Double):List[Int] = remain match {
        case Seq(a, _*) if a > limit => primelist:::remain
        case Seq(a, _*) => primemain(primelist:::List(a), remain.tail.filter(x => x % a != 0), limit)
        case _ => primelist
    }
    def prime(n: Int):List[Int] = primemain(List(), (2 to n).toList, sqrt(n))
    
    val n = sc.nextInt()
    println(prime(n))
}