Project Euler: Problem 14

Euler0014.scala

package euler.zerosum

object Euler0014 {
  def main(args: Array[String]) {
    println(
      (1 until 1000000).map(x => solveCollatz(x, x, 0)).maxBy(_._2)._1
    )
  }

  def solveCollatz(i: Long, tmp: Long, counter: Long): (Long, Long) = {
    if (tmp == 1) {
      (i, counter)
    } else if (tmp%2 == 0) {
      solveCollatz(i, tmp/2, counter+1)
    } else {
      solveCollatz(i, tmp*3+1 ,counter+1)
    }
  }
}