roman to integer conversion

Test.scala

/**
  * Created by rajeevprasanna on 11/2/17.
  */
object test extends App {

  // I -> 1
  // V -> 5
  // X -> 10
  // L -> 50
  // C -> 100
  // D -> 500
  // M -> 1000

  val romanNumbersMap = List(
    (1, "I"),
    (4, "IV"),
    (5, "V"),
    (9, "IX"),
    (10, "X"),
    (40, "XL"),
    (50, "L"),
    (90, "XC"),
    (100, "C"),
    (400, "CD"),
    (500, "D"),
    (900, "CM"),
    (1000, "M")
  )

  def reduceToRoman(a:Int, res:String, romanNumberVal:Int, romanStr:String):(Int, String) = {
    if(a >= romanNumberVal){
      reduceToRoman(a-romanNumberVal, res+romanStr, romanNumberVal, romanStr)
    }else{
      (a, res)
    }
  }
  def intToRoman(num:Int):String = romanNumbersMap.reverse.foldLeft((num, ""))((res, elem) => reduceToRoman(res._1, res._2, elem._1, elem._2))._2



}