unmix.clj

;; - unmix1 is my go-to solution
;; - unmix2 is 21% faster than unmix1
;; - unmix3 is 212% faster than unmix1
;; - unmix3 is a classic car-cdr lispy solution
;;
;; Benchmarked with criterium

(defn unmix1 [s]
  (reduce (fn [memo [a b]] (str memo b a))
          ""
          (partition-all 2 s)))

;; Results for unmix1
;;
;; Evaluation count : 5196780 in 60 samples of 86613 calls.
;;              Execution time mean : 11,874229 µs
;;     Execution time std-deviation : 372,407530 ns
;;    Execution time lower quantile : 11,389739 µs ( 2,5%)
;;    Execution time upper quantile : 12,736383 µs (97,5%)
;;                    Overhead used : 7,558749 ns

(defn unmix2 [s]
  (loop [[a b] (take 2 s)
         s (nthrest s 2)
         memo ""]
    (if (or a b)
      (recur
       (take 2 s)
       (nthrest s 2)
       (str memo b a))
      memo)))

;; Results for unmix2
;;
;; Evaluation count : 6179220 in 60 samples of 102987 calls.
;;              Execution time mean : 9,805924 µs
;;     Execution time std-deviation : 219,493487 ns
;;    Execution time lower quantile : 9,574716 µs ( 2,5%)
;;    Execution time upper quantile : 10,450540 µs (97,5%)
;;                    Overhead used : 7,558749 ns

(defn unmix3 [s]
  (loop [a (first s)
         b (second s)
         s (rest (rest s))
         memo ""]
    (if (or a b)
      (recur
       (first s)
       (second s)
       (rest (rest s))
       (str memo b a))
      memo)))

;; Results for unmix3
;;
;; Evaluation count : 15704100 in 60 samples of 261735 calls.
;;              Execution time mean : 3,800963 µs
;;     Execution time std-deviation : 65,247816 ns
;;    Execution time lower quantile : 3,745129 µs ( 2,5%)
;;    Execution time upper quantile : 3,986512 µs (97,5%)
;;                    Overhead used : 7,558749 ns