gistfile1.clj

(defn divides?
  "Does divisor divide dividend evenly?"
  [dividend divisor]
  (zero? (rem dividend divisor)))
 
(defn factors
  "Returns a sequence of all factors of p."
  [p]
  (filter #(divides? p %) (range 2 p)))

(defn prime?
  "Returns true if p is prime, false otherwise."
  [p]
  (empty? (factors p)))

(defn medians
  "Returns the two middle numbers of list."
  [lis]
  (if (empty? lis)
    '()
    (list (nth lis (/ (- (count lis) 1) 2))
          (nth lis (/ (count lis) 2)))))

(defn check-answer
  "Checks that the two factors equal the number."
  [fac1 fac2 num]
  (= (* fac1 fac2) num))

(defn squarest-factors
  "Pass num and find the most square factors."
  [num]
  (if (prime? num)
    (printf "1 * %d = %d \n" num num)
    (let [nums (medians (factors num))]
      (if (check-answer (first nums) (last nums) num)
        (printf "%d * %d = %d \n" (first nums) (last nums) num)
        (print "FAIL")))))

; Run it
(time (squarest-factors 8276345))