Data commit

Task/Move-to-front-algorithm/Clojure/move-to-front-algorithm.clj

@@ -0,0 +1,21 @@
+(def lowercase (map char (range (int \a) (inc (int \z)))))
+
+(defn move-to-front [x xs]
+  (cons x (remove #{x} xs)))
+
+(defn encode [text table & {:keys [acc] :or {acc []}}]
+  (let [c (first text)
+        idx (.indexOf table c)]
+    (if (empty? text) acc (recur (drop 1 text) (move-to-front c table) {:acc (conj acc idx)}))))
+
+(defn decode [indices table & {:keys [acc] :or {acc []}}]
+  (if (empty? indices) (apply str acc)
+    (let [n (first indices)
+          c (nth table n)]
+      (recur (drop 1 indices) (move-to-front c table) {:acc (conj acc c)}))))
+
+(doseq [word ["broood" "bananaaa" "hiphophiphop"]]
+  (let [encoded (encode word lowercase)
+        decoded (decode encoded lowercase)]
+    (println (format "%s encodes to %s which decodes back to %s."
+                   word encoded decoded))))