PIS Study Euler Problem2

import scala.annotation.tailrec

object Problem2 {

  def fib(n: Int): Int = {
    @tailrec
    def run(n: Int, i: Int = 1, acc1: Int = 1, acc2: Int = 1): Int = {
      if(n <= i) acc1
      else run(n, i+1, acc2, acc1 + acc2)
    }

    if (n < 2) n else run(n)
  }

  @tailrec
  def fibSum(max: Int, sum: Int = 0, num: Int = 2): Int = {
    fib(num) match {
      case n if n > max => sum
      case n if n % 2 == 0 => fibSum(max, sum + n, num+1)
      case _ => fibSum(max, sum, num+1)
    }
  }                                               //> fibSum: (max: Int)Int
  fibSum(4000000)                                 //> res0: Int = 4613732
}