Primes.scala

object Primes extends App {

  def process(A: List[Int], B: List[Int]) = {

    def isPrime(n: Int): Boolean = {
      if (n == 2) true
      else if (n < 2 || n % 2 == 0) false
      else Stream.from(3, 2).takeWhile(i => i * i <= n).forall(n % _ != 0)
    }

    val map = scala.collection.mutable.Map[Int, Int]()
    B.foreach(i => {
      val count = if (map contains i) map(i) else 0
      map.put(i, count + 1)
    })

    A.filter(i => !B.contains(i) || !isPrime(map(i)))
  }

  //example 
  val A = List(2, 3, 9, 2, 5, 1, 3, 7, 10)
  val B = List(2, 1, 3, 4, 3, 10, 6, 6, 1, 7, 10, 10, 10)
  process(A, B)
  
}