https://codeiq.jp/q/1368 の問題をscalaで解きました

難関中学受験問題を解こう.scala

case class Fraction(numer:Int,denom:Int){
    import scala.annotation._
    
    @tailrec
    private def gcd(a:Int,b:Int):Int= b match{
        case 0 => a
        case _ => gcd(b,a%b)
    }

    def toAnswer:Int = {
        val n = numer/gcd(numer,denom)
        val d = denom/gcd(numer,denom)
        
        if(numer%denom==0){
            n/d
        }else{
            if(numer<denom){
                n + d
            }else{
                n/d + n%d + d
            }
        }
    }
    
}

object Application extends App {
    
    val answers = for{
         i <- (1 to 2015)
         if Fraction(i,27).toAnswer == 54
    }yield i
    
    val first5th = answers(4)
    val last5th = answers.reverse.apply(4)
    
    println(first5th+"\n"+last5th)
    
    
}