--- a/testing1/collatz.scala Tue Nov 19 06:38:20 2019 +0000
+++ b/testing1/collatz.scala Fri Nov 22 16:41:45 2019 +0000
@@ -6,48 +6,18 @@
// If needed, you can use an auxiliary function that
// performs the recursion. The function should expect
// arguments in the range of 1 to 1 Million.
+def stepsCounter(n: Long, s: Long) : Long = n match{
+ case 1 => s
+ case n if(n%2==0) => stepsCounter(n/2,s+1)
+ case _ => stepsCounter(3*n+1, s+1)
+}
+
+def collatz(n: Long) : Long = n match {
+ case n if(n>0) => stepsCounter(n,0)
+ case n if(n<=0) => stepsCounter(1,0)
+}
-// def collatz(n: Long) : Long = {
-// if (n == 1) 1 //else
-// // if (n % 2 == 0) {
-// // collatz(n/2)
-// // steps + 1
-// // } //else
-// // if (n % 2 != 0) {
-// // collatz((3 * n) + 1)
-// // steps + 1
-// // }
-// }
-
-// val steps: Long = 1
-// val lst = List()
-// def collatz(n: Long) : Long = {
-// if (n == 1) { steps + 1 }
-// else if (n % 2 == 0) {
-// collatz(n/2);
-// }
-// else {
-// collatz((3 * n) + 1);
-// }
-// steps + 1
-// }
-// collatz(6)
-
-def collatz(n: Long, list: List[Long] = List()): Long = {
- if (n == 1) {
- n :: list
- list.size.toLong
- }
- else if (n % 2 == 0) {
- collatz(n / 2, n :: list)
- }
- else {
- collatz((3 * n) + 1, n :: list)
- }
-}
-
-val test = collatz(6)
//(2) Complete the collatz_max function below. It should
// calculate how many steps are needed for each number
@@ -58,13 +28,10 @@
// the maximum number of steps and the second is the
// corresponding number.
-//def collatz_max(bnd: Long) : (Long, Long) = ...
-def collatz_max(bnd: Long) : (Long, Long) = {
- val stepsTable = for (n <- (1 to bnd.toInt).toList) yield (collatz(n), n.toLong)
- //println(stepsTable)
- stepsTable.max
+def collatz_max(bnd: Long) : (Long, Long) = {
+ val allCollatz = for(i<-1L until bnd) yield collatz(i)
+ val pair = (allCollatz.max, (allCollatz.indexOf(allCollatz.max) +1).toLong)
+ pair
}
-
}
-