1 // Part 1 about the 3n+1 conjecture

     2 //==================================

     3 

     4 

     5 object CW6a { // for purposes of generating a jar

     6 

     7 def collatz(n: Long): Long =

     8   if (n == 1) 0 else

     9     if (n % 2 == 0) 1 + collatz(n / 2) else 

    10       1 + collatz(3 * n + 1)

    11 

    12 

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

    14   val all = for (i <- (1L to bnd)) yield (collatz(i), i)

    15   all.maxBy(_._1)

    16 }

    17 

    18 

    19 /* some test cases

    20 val bnds = List(10, 100, 1000, 10000, 100000, 1000000)

    21 

    22 for (bnd <- bnds) {

    23   val (steps, max) = collatz_max(bnd)

    24   println(s"In the range of 1 - ${bnd} the number ${max} needs the maximum steps of ${steps}")

    25 }

    26 

    27 */

    28 

    29 }