The following solution by <b>mtgred</b> for <a href="http://clojure-
euler.wikispaces.com/">Project Euler Clojure</a> problem 003 uses
implicit recursion.
<pre>
(use '[clojure.contrib.lazy-seqs :only (primes)])
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(if (= f n) #{f} (conj (prime-factors (/ n f)) f))))
(apply max (prime-factors 600851475143))
</pre>
Here is above with added println
(defn prime-factors [n]
(let [f (some #(if (= 0 (rem n %)) %) primes)]
(println "n:" n ", f:" f)
(if (= f n)
#{f}
(conj (prime-factors (/ n f)) f))))
Which produces
n: 600851475143 , f: 71
n: 8462696833 , f: 839
n: 10086647 , f: 1471
n: 6857 , f: 6857
#{71 839 6857 1471}
Can anybody explain why 6857 comes 3rd? I would expect to be the last.
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