A solution for #53 of 4clojure

4clojure-s53.clj

(require '[clojure.test :refer :all])

(def s53
  ; If you are in 4clojure paste from here
  (fn [coll]
    (->> coll
      ; 1st. Make tails of coll.
      (#(take-while identity (iterate next %)))
      ; 2nd. Take only consecutive elements from the head for each list.
      (map (fn [[c & cs]]
             (loop [[x & xs] cs acc [c] z c]
               (if (= (inc z) x) (recur xs (conj acc x) x) acc))))
      ; 3rd. Take only vectors having 2 or more elements.
      (filter #(< 1 (count %)))
      ; 4th. Take the longest. Take the one appearing first if 2 or more have a same length.
      (reduce #(if (< (count %2) (count %)) % %2) [])
    ))
  ; to here.
)

(deftest s53-test
  (is (= (s53 [1 0 1 2 3 0 4 5]) [0 1 2 3]))
  (is (= (s53 [5 6 1 3 2 7]) [5 6]))
  (is (= (s53 [2 3 3 4 5]) [3 4 5]))
  (is (= (s53 [7 6 5 4]) [])))

http://www.4clojure.com/problem/53