The major problem here is that you are using boxed math for everything instead of primitives.
0) Switch to Clojure 1.7.0-beta3 - it's faster and some things below are dependent on it for best performance. And use Java 1.8. 1) Parse the lines you're reading directly into longs (Clojure focuses on 64-bit primitives - longs and doubles) 2) Put the longs first into a data structure that preserves the primitive type. The two best options for that here are records (which can have primitive fields) and arrays. I would create a Canvas defrecord with ^long width and height and a Paper defrecord with all ^long fields for example. 3) Store the papers in a vector (using transient to create it) 4) I suspect visible-color and covered? could probably be tightened up into a reduce over papers or a single loop-recur over papers - can't say I totally get what's happening there. 5) In visible-color-frequencies, you could use "update" instead of get + transient assoc! on the acc map, but this is never going to be terribly fast. Another option here would be to create an array with the max color (you could track that while reading if it's not a well-known answer) and bash the array. That can retain int or long counters and will be *way* faster. 6) You can use (set! *unchecked-math* :warn-on-boxed) to get faster math (no overflow checks) and also issue warnings (added in 1.7) if you happened to use boxed math by accident. On Thursday, May 14, 2015 at 3:02:42 AM UTC-5, Amith George wrote: > > I wrote the following code to solve this challenge - > https://www.reddit.com/r/dailyprogrammer/comments/35s2ds/20150513_challenge_214_intermediate_pile_of_paper/ > . > > Code - > https://github.com/amithgeorge/reddit-dailyprogrammer-clojure/blob/56ce1dbb6a08e96150dc85934caecfeb68108a53/src/rdp/214_intermediate.clj > > I executed the -main function using `lein run 1`. > > Output > > ;; lein run 1 > > 0 12605919 > 1 3578145 > 2 15356894 > 3 19134293 > 4 2394558 > 5 15030409 > 6 6424953 > 7 14893444 > 8 1592254 > 9 1914025 > 10 7075106 > "Elapsed time: 501168.972435 msecs" > > The code originally used an immutable hashmap, but I lost patience waiting > for the computation to end. With mutable hashmap, it still takes around 8 > mins. > > I wrote a C# version of the above code - > https://gist.github.com/amithgeorge/766b8220f39d48221e58. It finishes > under 40secs. The C# exe was built under Release mode and executed directly > from the commandline. I expected the Clojure version to perform similarly. > > Any tips on what I am doing wrong? > > ----- > Explanation of the code - Create a vector of all paper sheets, such that > the sheet placed last is the first element of the vector and the last > element is the canvas. To compute the frequency of each visible color - for > each point in the canvas find the first sheet in the vector that covers the > point. Store/increment its count in the hashmap. I understand there might > be better more efficient ways to solve this, but currently I am interested > in why the Clojure versions is so slow vis-a-vis the C# version. > > -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
