Hi Marek, I think the (inc) in (decimal-fraction-digits) and the (dec) in (solution) cancel each other out, so the two functions can be simplified a bit to:
(defn decimal-fraction-digits [] "Returns the lazy sequence of digits in irrational fraction created by concatenating the positive integers" (mapcat digits (range))) (defn solution [] (reduce * (take 7 (map #(nth (decimal-fraction-digits) %) (iterate #(* 10 %) 1))))) On Feb 16, 7:17 am, Marek Stępniowski <mstepniow...@gmail.com> wrote: > On Wed, Feb 16, 2011 at 9:15 AM, Andreas Kostler > > <andreas.koestler.le...@gmail.com> wrote: > > Thanks for everyone who commented on my solution for Euler 28 yesterday. > > Euler 40 is a bit easier, even more so I'm disappointed with the > > performance of my solution:(defn euler-40 [n-max] > > > (reduce #(* (Integer/valueOf (str %1)) (Integer/valueOf (str %2))) > > (let [r (range (inc n-max))] > > (for [n (iterate #(* % 10) 1) :while (< n n-max)] (nth > > (apply str r) n))))) > > > It takes about 4s to find the solution. > > > First of all, I guess the whole Integer/valueOf ceremony doesn't affect > > performance but could probably be dealt with in a more idiomatic way. > > Other than that, how could I optimise the presented solution. Hints to > > other solutions (as long as they're pretty ;)) are also welcome :) > > My > solutionhttps://github.com/zuber/project-euler/blob/master/src/com/stepniowsk... > takes ~800 ms on my computer. It's basically the same, but I believe > it minimalizes the number of conversions from int to string. > > Cheers, > -- > Marek Stępniowskihttp://stepniowski.com -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
