Problem 10

src/main/scala/ninetyNineScalaProblems/Problem10.scala

@@ -0,0 +1,15 @@
+package ninetyNineScalaProblems
+
+import scala.annotation.tailrec
+
+object Problem10:
+    def runLengthEncode(list: List[Any]): List[Tuple2[Int, Any]] =
+        @tailrec
+        def loop(cursor: List[List[Any]], acc: List[Tuple2[Int, Any]]): List[Tuple2[Int, Any]] =
+            cursor match
+                case d :: tail =>
+                    loop(tail, (d.length, d(0)) :: acc)
+                case Nil =>
+                    acc
+
+        loop(Problem09.consecutiveDuplicatesIntoSublists(list), List()).reverse

src/test/scala/ninetyNineScalaProblems/Problem10Suite.scala

@@ -0,0 +1,17 @@
+package ninetyNineScalaProblems
+
+import scala.compiletime.ops.boolean
+
+class Problem10Suite extends munit.FunSuite:
+    List(
+        (List(1, 2, 3, 4), List((1, 1), (1, 2), (1, 3), (1, 4))),
+        (List(1, 2, 2, 3), List((1, 1), (2, 2), (1, 3))),
+        (List(1, 2, 3, 2), List((1, 1), (1, 2), (1, 3), (1, 2))),
+        (List(), List()),
+        (List(1), List((1, 1))),
+        (List(1, 1, 1), List((3, 1))),
+        (List(1, 1, 1, 1, 2, 3, 3, 1, 1, 4, 5, 5, 5, 5), List((4, 1), (1,2), (2, 3), (2, 1), (1, 4), (4, 5)))
+    ).foreach:
+        case (list, expected) =>
+            test(s"runLengthEncoding returns [$expected]"):
+                assertEquals(Problem10.runLengthEncode(list), expected)