Euler Project: Problem 3 in Clojure

This is my solution in Clojure to the third problem from Euler project:

	(def factor?
	(comp zero? rem))
	(defn prime-factors [n]
	(loop [n n prime 2 factors #{}]
	(cond
	(= n 1) factors
	(factor? n prime) (recur (/ n prime) prime (conj factors prime))
	:else (recur n (inc prime) factors))))
	(prime-factors 35) ; #{5 7}
	(prime-factors 24) ; #{2 3}
	(prime-factors 600851475143) ; #{71 839 6857 1471}
	(apply max (prime-factors 600851475143)) ; 6857
	(defn largests-prime-factor [n]
	(apply max (prime-factors n)))
	(largests-prime-factor 600851475143) ; 6857

view raw euler-3.clj hosted with ❤ by GitHub

The largests-prime-factor function can be also written in this alternative way using Clojure's ->> macro:

	(defn largests-prime-factor [n]
	(->>
	n
	(prime-factors)
	(apply max)))

view raw euler-3-b.clj hosted with ❤ by GitHub