Scala : add 11-pack to sandbox

2 files changed, 20 insertions, 0 deletions

diff --git a/Scala/sandbox/0-main.scala b/Scala/sandbox/0-main.scala
index 1061f50..4414f12 100644
--- a/Scala/sandbox/0-main.scala
+++ b/Scala/sandbox/0-main.scala
@@ -13,5 +13,6 @@ object Main  extends App {
     PatternMatching.run
     Lists.run
     MergeSort.run
+    Pack.run
 
 }
diff --git a/Scala/sandbox/11-pack.scala b/Scala/sandbox/11-pack.scala
new file mode 100644
index 0000000..d593efd
--- /dev/null
+++ b/Scala/sandbox/11-pack.scala
@@ -0,0 +1,19 @@
+object Pack
+{
+
+  def pack[T](xs: List[T]): List[List[T]] = xs match {
+    case Nil      => Nil
+    case x :: xs1 =>
+    val (first, last) = xs span(y => y == x) // takeWhile + dropWhile
+    first :: pack(last)
+  }
+
+  def encode[T](xs: List[T]): List[(T,Int)] = pack(xs) map (ys => (ys.head, ys.length))
+
+  def run = {
+    println("Pack")
+    val l = List("a", "a", "a", "b", "c", "c", "a")
+    println(pack(l))
+    println(encode(l))
+  }
+}