euler02.scala

import scala.annotation.tailrec
import scala.collection.mutable

object Euler02 extends App {

  @tailrec
  def fib(num: Int, prev: Int, result: mutable.Builder[Int, Vector[Int]] = Vector.newBuilder[Int]): Vector[Int] = {
    num match {
      case 0 => result.result()
      case x if x > 4000000 => result.result()
      case x if x >= 1 => {
        if(num%2 == 0) result += x
        fib(x + prev, x, result)
      }
    }
  }

  print(fib(1, 0).sum)
}