CodeIQ_Collatz.scala

object CodeIQ_Collatz {
  val d = (n: Int) => n / 2
  val m = (n: Int) => n * 3 + 1

  def ev(n: Int) =
    if (n % 2 == 0)
      d(n)
    else
      m(n)

  def e(i: Int): Boolean = {
    var r = m(i)
    while (r != 1) {
      if (r == i)
        return true
      r = ev(r)
    }
    false
  }

  def main(args: Array[String]) = print(Range(2, 10000, 2).count(p => e(p)))
}