Sequence-of-Pronunciations.clj

;; dkawashima's solution to Sequence of Pronunciations #110
;; https://4clojure.com/problem/110

;; Write a function that returns a lazy sequence of "pronunciations" of a sequence of numbers. 
;; A pronunciation of each element in the sequence consists of the number of repeating identical 
;; numbers and the number itself. For example, [1 1] is pronounced as [2 1] ("two ones"), 
;; which in turn is pronounced as [1 2 1 1] ("one two, one one").

;; Your function should accept an initial sequence of numbers, and return an infinite lazy sequence of pronunciations, 
;; each element being a pronunciation of the previous element.

(defn sequenceofPronunciations
  [vect]
  (let [resVec (vec (interleave (map count (partition-by identity vect)) (flatten (map distinct (partition-by identity vect)))))]
      (cons resVec (lazy-seq (sequenceofPronunciations resVec ))))
  )

;; Test Cases:

(= [[1 1] [2 1] [1 2 1 1]] (take 3 (sequenceofPronunciations [1])))

(= [3 1 2 4] (first (sequenceofPronunciations [1 1 1 4 4])))

(= [1 1 1 3 2 1 3 2 1 1] (nth (sequenceofPronunciations [1]) 6))

(= 338 (count (nth (sequenceofPronunciations [3 2]) 15)))