prime-factors.clj

prime-factors.clj

(ns factors.core-spec
  (:require [speclj.core :refer :all]
            [factors.core :refer :all]))

(defn factors-of [n]
  (loop [n n, d 2, fs []]
    (cond (= n 1) fs
          (zero? (mod n d)) (recur (/ n d) d (conj fs d))
          :else (recur n (inc d) fs))))

(describe "Prime Factors Kata"
  (it "computes prime factors"
    (->> (factors-of 1) (should= []))
    (->> (factors-of 2) (should= [2]))
    (->> (factors-of 3) (should= [3]))
    (->> (factors-of 4) (should= [2 2]))
    (->> (factors-of 5) (should= [5]))
    (->> (factors-of 6) (should= [2 3]))
    (->> (factors-of 7) (should= [7]))
    (->> (factors-of 8) (should= [2 2 2]))
    (->> (factors-of 9) (should= [3 3]))
    (->> (factors-of 10) (should= [2 5]))
    (->> (factors-of (* 2 3 5 7 11 13 17))
              (should= [2 3 5 7 11 13 17]))))