Project Euler: Problem 9

Euler0009.scala

object Euler0009 {

  private val max = 1000

  def main(args: Array[String]): Unit = {
    println(
      buildTriplets(1, 2, Nil).filter(_.isPitagolyan).map(_.product)
      )
  }

  private class Triplet(val a: Int, val b: Int, val c: Int) {

    def isPitagolyan(): Boolean = {
      a*a + b*b == c*c
    }

    def product() : Int = {
      a * b * c
    }
  }

  private def buildTriplets(a: Int, b: Int, triplets: List[Triplet]): List[Triplet] = {
    val c = max - a - b

    if(a > max/3) {
      triplets
    } else if(b < c) {
      buildTriplets(a, b+1, new Triplet(a, b, c) :: triplets)
    } else {
      buildTriplets(a+1, a+2, triplets)
    }
  }
}