secret-string solution

secret-string.clj

;; 1. Get each of the characters from the triplet as keys to a hash-map 
;; 2. The values are the characters before the key character in the secret string. 
;; 3. Find the key which has no values.
;; 4. Add that character to the final string
;; 5. Remove it from the hash-map, and all instances of it from the map values.
;; 6. Goto 3
;; 7. Once hash-map has no keys left. We are done!

(ns codewars.puzzle-strings
  (:require [clojure.set :as set]
            [com.rpl.specter :as sc]))

(defn recover-secret [xs]
  (loop [result ""
         remaining (reduce #(as-> (update %1 (second %2)  conj (first %2)) o
                                  (update o  (nth %2 2)   conj (first %2) (second %2))
                                  (update o  (first %2)   (fnil conj []))) {} xs)]
    (let [curr ((set/map-invert remaining) [])]
      (cond (nil? curr) result
            :else (recur (str result curr) (sc/setval (sc/walker (fn [x] (= curr x))) sc/NONE remaining))))))