September 2017 Update

Task/Caesar-cipher/Kotlin/caesar-cipher.kotlin

@@ -0,0 +1,35 @@
+// version 1.0.5-2
+
+object Caesar {
+    fun encrypt(s: String, key: Int): String {
+        val offset = key % 26
+        if (offset == 0) return s
+        var d: Char
+        val chars = CharArray(s.length)
+        for ((index, c) in s.withIndex()) {
+            if (c in 'A'..'Z') {
+                d = c + offset
+                if (d > 'Z') d -= 26
+            }
+            else if (c in 'a'..'z') {
+                d = c + offset
+                if (d > 'z') d -= 26
+            }
+            else
+                d = c
+            chars[index] = d
+        }
+        return chars.joinToString("")
+    }
+
+    fun decrypt(s: String, key: Int): String {
+        return encrypt(s, 26 - key)
+    }
+}
+
+fun main(args: Array<String>) {
+    val encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8)
+    println(encoded)
+    val decoded = Caesar.decrypt(encoded, 8)
+    println(decoded)
+}