116 Prime Sandwich times out

[Jim Altieri]

Hey folks,

I know my solution is probably not the best, but it executes on my machine pretty quickly. Am I doing anything obviously wrong?

(fn [x] (let [prime? (fn [n] (if (= 2 n)

                               true

                               (not-any? #(zero? (rem n %)) (concat '(2) (range 3 (+ 1 (int (Math/sqrt n))))))))

               nextprime (fn [n] (if (= 2 n)

                                  3

                                  (some #(if (prime? %) %) (iterate (partial + 2) (+ n 2)))))]

           (if (>= x 5)

             (if (prime? x)

               (let [prev (do (- x (- (nextprime x) x)))]

                 (and (prime? prev) (= (nextprime prev) x)))

               false)

             false)))

[hak]

java functions, like Math/sqrt will kill the performance on 4clojure

replace (+ 1 (int (Math/sqrt n))) with n and it will work