Clojure solution for https://www.hackerrank.com/challenges/sequence-full-of-colors

sequence-full-of-colors.clj

(ns hackerrank.sequence-full-of-colors.core)

(defn count-color [codes color]
  (->> codes 
       (filter  #(= color %)) 
       (count)))

(defn eq [codes & colors]
  (->> colors
       (map #(count-color codes %))
       (apply =)))

(defn prefix-diff [check-fn codes colors]
  (->> colors
       (map #(count-color codes %))
       (apply -)
       (Math/abs)
       (check-fn)))

(defn diff<=? [limit codes & colors]
  (->> codes
       (reduce (fn [[result current] code]
                 (if (prefix-diff #(<= % limit) current colors)
                   [result (conj current code)]
                   (reduced [false])))
               [true []])
       (first)))

(defn full-of-colors? [codes]
  (and (eq codes \R \G)
       (eq codes \Y \B)
       (diff<=? 1 codes \R \G)
       (diff<=? 1 codes \Y \B)))

(comment
  (map full-of-colors? ["RGGR" "RYBG" "RYRB" "YGYGRBRB"]))