[Scala][Algorithm] 用Scala找質數的範例

FindPrimse.scala

object FindPrimse {

  def main(args: Array[String]) {
    val result = fillPrimeList(10000)
    result foreach println
  }

  def fillPrimeList(max: Int, list: List[Int] = List(3, 2)): List[Int] = {
    if (list.head < max)
      fillPrimeList(max, findNextPrime(list, list.head + 2) :: list)
    else
      list
  }

  def findNextPrime(primeList: List[Int], nextNumber: Int): Int = {
    val upperBound = math.sqrt(nextNumber)
    if (primeList.filter(_ <= upperBound) exists (nextNumber % _ == 0))
      findNextPrime(primeList, nextNumber + 2)
    else
      nextNumber
  }
}