Project Euler by scala No.32

Euler32.scala

package ssbt

object Euler32 {

  def main(args: Array[String]) {
    val permutations = List("1", "2", "3", "4", "5", "6", "7", "8", "9").permutations
    val pandigitalProducts = permutations.map(getPandigitalProductList(1, _)).toList.filter(_.size > 0)

    println("Answer %s".format(pandigitalProducts.flatten.distinct.sum))
  }

  private def getPandigitalProductList(takeIndex: Int, permutaion: List[String], products: List[Int] = List[Int]()): List[Int] = {
    if (takeIndex > permutaion.size / 2) {
      products
    } else {
      val pd = getPandigitalProduct(permutaion.take(takeIndex).mkString, 1, permutaion.drop(takeIndex))
      getPandigitalProductList(takeIndex + 1, permutaion, pd ::: products)
    }
  }

  private def getPandigitalProduct(firstMultiply: String, takeIndex: Int, list: List[String], products: List[Int] = List[Int]()): List[Int] = {
    if (list.size - firstMultiply.length < takeIndex) {
      products
    } else {
      val secondMultiply = list.take(takeIndex).mkString
      val product = list.drop(takeIndex).mkString
      val pd = if (firstMultiply.toInt * secondMultiply.toInt == product.toInt) product.toInt +: products else products
      getPandigitalProduct(firstMultiply, takeIndex + 1, list, pd)
    }
  }

}