Created
May 17, 2012 08:15
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Inverse Fizzbuzz solver in Clojure
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;; Question: Inverse FizzBuzz (Clojure version) - Given a collection | |
;; whose elements are one of :fizz, :buzz, and :fizzbuzz, what's the | |
;; shortest contiguous sequence of numbers that produces that list when | |
;; you run fizzbuzz ? | |
;; | |
;; Originally introduced at: | |
;; http://www.jasq.org/2/post/2012/05/inverse-fizzbuzz.html | |
(ns tnoda.inverse-fizzbuzz.core | |
(:use [clojure.test :only [deftest are]])) | |
(defn- fizzbuzz [n] | |
(cond (zero? (mod n 15)) :fizzbuzz | |
(zero? (mod n 3)) :fizz | |
(zero? (mod n 5)) :buzz)) | |
(defn- fizzbuzz-seq [length] | |
(comp (juxt (partial map first) (partial map second)) | |
(partial take length) | |
(partial filter first) | |
(partial map (juxt fizzbuzz identity)) | |
(partial iterate inc) | |
inc)) | |
(defn- triple [coll] | |
(comp (partial cons coll) | |
(fizzbuzz-seq (count coll)))) | |
(defn- triples [coll] | |
(map (triple coll) [0 3 5 6 9 10 12])) | |
(defn- match? [[expected actual _]] | |
(= expected actual)) | |
(defn- actual-length [s] | |
(- (last (last s)) (first (last s)))) | |
(def solve | |
(comp (juxt first last) | |
last | |
first | |
(partial sort-by actual-length) | |
(partial filter match?) | |
triples)) | |
(deftest test-solve | |
(are [x y] (= (solve x) y) | |
[:fizz] [3 3] | |
[:fizz :buzz] [9 10] | |
[:buzz :fizz :fizz] [5 9] | |
[:fizz :fizz :buzz] [6 10] | |
[:fizzbuzz :fizz] [15 18] | |
[:fizzbuzz :fizzbuzz] [nil nil] | |
[:fizz :buzz :fizz :fizz :buzz] [3 10])) |
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