Problem 09

2026-03-19 15:39:22 +01:00
parent 659d211d8c
commit 7e6ea14b44
2 changed files with 120 additions and 0 deletions
@@ -0,0 +1,66 @@
+package ninetyNineScalaProblems
+
+import scala.annotation.tailrec
+
+object Problem09:
+    def sameValueRepeatedAnyTime(list: List[Any]): Boolean =
+        @tailrec
+        def loop(cursor: List[Any], acc: Boolean): Boolean =
+            cursor match
+                case List(x) =>
+                    true
+                case x1 :: List(x2) if x1 == x2 =>
+                    true
+                case x1 :: x2 :: tail if x1 == x2 =>
+                    loop(x1 :: tail, true)
+                case x :: tail =>
+                    false
+                case Nil =>
+                    true
+
+        loop(list, true)
+
+    def countRepititions(list: List[Any]): Int =
+        @tailrec
+        def loop(cursor: List[Any], acc: Int): Int =
+            cursor match
+                case e1 :: e2 :: Nil if e1 == e2 =>
+                    acc + 2
+                case e1 :: e2 :: tail if e1 == e2 =>
+                    loop(e2 :: tail, acc + 1)
+                case e :: tail =>
+                    acc + 1
+                case Nil =>
+                    acc
+
+        loop(list, 0)
+
+    def nthElementToEnd(list: List[Any], n: Int): List[Any] =
+        @tailrec
+        def loop(cursor: List[Any], acc: List[Any], position: Int): List[Any] =
+            cursor match
+                case e :: tail if position >= n =>
+                    loop(tail, e :: acc, position + 1)
+                case e :: tail =>
+                    loop(tail, acc, position + 1)
+                case Nil =>
+                    acc
+
+        loop(list, List(), 0).reverse
+
+    def consecutiveDuplicatesIntoSublists(list: List[Any]): List[List[Any]] =
+        @tailrec
+        def loop(cursor: List[Any], acc: List[List[Any]]): List[List[Any]] =
+            val repititions = countRepititions(cursor)
+            cursor match
+                case Nil =>
+                    acc
+                case _ if repititions == 0 =>
+                    acc
+                case _ => cursor match
+                    case e :: tail =>
+                        loop(nthElementToEnd(tail, repititions - 1), List.fill(repititions)(e) :: acc)
+                    case Nil =>
+                        acc
+
+        loop(list, List()).reverse