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