Euler_014.scala

object Euler_014 extends App {

  def collatz(curNum:BigInt, times:Int = 1):Int = {
    if(curNum equals 1) return times
    if(curNum%2 equals 0) collatz(curNum/2, times+1)
    else collatz(3*curNum+1, times+1)
  }

  val result = (1 to 1000000).map(collatz(_))
  println(result.indexOf(result.max)+1)

}