345 // Avoid being mutable

   345 // Avoid being mutable

   346 //=====================

   346 //=====================

   347 

   347 

   348 // a student showed me...

   348 // a student showed me...

   349 import scala.collection.mutable.ListBuffer

   349 import scala.collection.mutable.ListBuffer

   350 

   352 

   351 def collatz_max(bnd: Long): (Long, Long) = {

   353 def collatz_max(bnd: Long): (Long, Long) = {

   352   val colNos = ListBuffer[(Long, Long)]()

   354   val colNos = ListBuffer[(Long, Long)]()

   353   for (i <- (1L to bnd).toList) colNos += ((collatz(i), i))

   355   for (i <- (1L to bnd).toList) colNos += ((collatz(i), i))

   354   colNos.max

   356   colNos.max