diff -r fdc2c6fb7a24 -r 9891c9fac37e progs/collatz_sol2.scala
--- a/progs/collatz_sol2.scala	Tue Nov 15 23:08:09 2016 +0000
+++ b/progs/collatz_sol2.scala	Wed Nov 16 14:37:18 2016 +0000
@@ -15,7 +15,7 @@
 
 
 // an alternative that calculates the steps directly
-def collatz1(n: Long): Int =
+def collatz1(n: Long): Long =
   if (n == 1) 1 else
     if (n % 2 == 0) (1 + collatz1(n / 2)) else 
       (1 + collatz1(3 * n + 1))
@@ -37,13 +37,15 @@
 //     upto 1 million. 
 
 def collatz_max(bnd: Long): (Long, Long) = {
-  (1L to bnd).view.map((i) => (collatz2(i, 1), i)).maxBy(_._1)
+  (1L to bnd).view.map((i) => (collatz1(i), i)).maxBy(_._1)
 }
 
 
 // some testing harness
 //val bnds = List(10, 100, 1000, 10000, 100000, 1000000)
-val bnds = List(10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000)
+val bnds = List(10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 2000000000)
+
+
 
 for (bnd <- bnds) {
   val (steps, max) = collatz_max(bnd)