peteris-4clojure-solution31.clj

;; peteris's solution to http://4clojure.com/problem/31

#(let [[elt cnt] 
      (let [v (vec %), n (count %)]
       (loop [i 1, elt [(first v)], cnt [1]]
         (if (= i n)
           [elt cnt]
           (recur (inc i)
                  (if (= (v i) (v (dec i)))
                    elt
                    (conj elt (v i)))
                  (if (= (v i) (v (dec i)))
                    (assoc cnt (dec (count cnt)) (inc (cnt (dec (count cnt)))))
                    (conj cnt 1))))))]
    (for [i (range (count elt))]
      (take (cnt i) (repeat (elt i)))))