Add Kotlin example

Makefile

@@ -49,6 +49,10 @@ scala: CompressionPuzzle01.class CompressionPuzzle02.class
 	scala CompressionPuzzle01
 	scala CompressionPuzzle02
 
+# Kotlin
+kotlin:
+	kotlinc -script src/kotlin/compress.kts
+
 rye: rye-build
 	./rye-src/rye src/rye/compress_jm_rec.rye
 	./rye-src/rye src/rye/compress_jm_rec_steps.rye

README.md

@@ -51,6 +51,7 @@ make python
 make ruby
 make rye
 make scala
+make kotlin
 ```
 
 ## Authors
@@ -67,4 +68,5 @@ make scala
 - [Simon Belak](https://github.com/sbelak)
 - [Tit Petrič](https://github.com/titpetric)
 - [Urban Škudnik](https://github.com/uskudnik)
+- [Jernej Virag](https://github.com/izacus)
 

shell.nix

@@ -12,6 +12,7 @@ stdenv.mkDerivation {
       python3
       ruby_3_0
       scala
+      kotlin
     ];
     shellHook = ''
     '';

src/kotlin/compress.kts

@@ -0,0 +1,20 @@
+fun compress(input: String): String {
+    // [A, A, A, B, B, A, A, C]
+ return input.chunked(1)
+    // ["AAA", "BB", "AA", "C"]
+    .fold(mutableListOf<String>(), { sequences, ch -> 
+        sequences.add(if (!sequences.isEmpty() 
+                           && sequences.last().contains(ch))
+                        sequences.removeLast().plus(ch)
+                    else
+                        ch)
+        sequences
+    })
+    // ["3A", "2B", "2A", "1C"]
+    .map({ it.length.toString() + it.first() })
+    // "3A2B2A1C"
+    .joinToString("")
+}
+
+if (compress("AAABBAAC") != "3A2B2A1C")
+    throw AssertionError()