progs/collatz.scala
changeset 15 52713e632ac0
parent 11 417869f65585
child 18 87e55eb309ed
--- a/progs/collatz.scala	Mon Nov 07 12:58:00 2016 +0000
+++ b/progs/collatz.scala	Tue Nov 08 10:30:42 2016 +0000
@@ -1,29 +1,23 @@
-// Part 1
+// Part 1 about the 3n+1 conceture
+//=================================
 
 
-//(1)
-def collatz(n: Long): List[Long] =
-  if (n == 1) List(1) else
-    if (n % 2 == 0) (n::collatz(n / 2)) else 
-      (n::collatz(3 * n + 1))
+//(1) Complete the collatz function below. It should
+//    recursively calculate the number of steps needed 
+//    until the collatz series reaches the number 1.
+//    If needed you can use an auxilary function that
+//    performs the recursion. The function should expect
+//    arguments in the range of 1 to 10 Million.
 
-// an alternative that calculates the steps directly
-def collatz1(n: Long): Int =
-  if (n == 1) 1 else
-    if (n % 2 == 0) (1 + collatz1(n / 2)) else 
-      (1 + collatz1(3 * n + 1))
+def collatz(n: Long): Int = ...
 
 
-//(2)
-def collatz_max(bnd: Int): Int = {
-  (for (i <- 1 to bnd) yield collatz(i).length).max
-}
+//(2)  Complete the collatz bound function below. It should
+//     calculuate how many steps are needed for each number 
+//     from 1 upto a bound and return the maximum number of
+//     steps. You should expect bounds in the range of 1
+//     upto 10 million. 
+
+def collatz_max(bnd: Int): Int = ...
 
 
-val bnds = List(10, 100, 1000, 10000, 100000, 1000000, 10000000)
-
-for (bnd <- bnds) {
-  val max = collatz_max(bnd)
-  println(s"In the range of 1 - ${bnd} the maximum steps are ${max}")
-}
-