Announcements (Search)

Rules on asking questions

by admin on Nov 15, 2011 - 1:47:11 pm UTC
  • (5/2)
Before you ask a question, please do the following:
  • Read this.
  • Java users: make sure you name your class the same thing as the problem code.
  • Be wary of carriage returns '\r' in test data. C/C++ users check for a trailing '\r' in strings you read with gets()/getline(), Python users use raw_input().strip() instead of input(), etc.
  • The status page will only let you preview a snippet of your output. "Your Output (clipped)" simply means that the preview was truncated.
  • Make sure your program works correctly on the sample input(s). It must match exactly!
  • Indent your code and use logical variable names if you want help.
  • Think about large or tricky test cases, and ensure your program can handle them properly.
  • Java users: if the answer to your question is xyzException, that means we deem the bug sufficiently trivial so that just knowing what the exception is should allow you to fix it.
  • Try to fix the problem yourself for at least 15 minutes before giving up and asking for help.
  • If you think the test data are incorrect, please take a moment and consult the Best Solutions page to see how many people have gotten the problem Accepted, and then ask yourself whether it would not be arrogant to conclude that your program is correct and everyone else's programs are wrong. (Of course, problem setters do screw up sometimes, by adding trailing space, or something like that; this may bite you if you're using a different programming language than everyone else. If you suspect that this may be the case, don't hesitate to speak up. However, be forewarned that this is almost always not the case whenever the input consists entirely of numbers.)

On asking questions: post on a problem page if and only if your question is of relevance to everybody (for instance, a clarification question). If your question pertains only to you (such as if your program doesn't work, or if there's something you don't understand about your programming language), please don't clutter up the comments page with it. Instead, consider posting on the forums or just asking a friend to look your program over.

PEG Members: Please do not post for help here. Instead, use the in-class resources and email your leaders for assistance.
If at any time you post a question asking for help in the comments section of a problem, we will delete and ignore it.

Also note: programs may behave differently on the judge and on your computer, but this almost always happens only because you have done Something Bad. Please review this checklist before assuming there is a grader bug and posting a comment about it.

Thank you for your cooperation.

mazel tov

by bbi5291 on Nov 06, 2011 - 5:27:44 am UTC
  • (9/0)
The Judge has reached 50000 submissions.

The 50000th submission was made by Alex on Nov 05/11, 4:44:49 PM EDT to the problem "BlueBook - World Pop" in Pascal. It received a score of 30/30.

by bbi5291 on Nov 06, 2011 - 3:51:58 am UTC
  • (3/0)
This box ( now runs an IRC server.
You can also use the web client at, if you are lame.

Multiple submissions of identical code

by bbi5291 on Oct 24, 2011 - 4:52:07 am UTC
  • (2/0)
A reminder not to do this. It clutters up the submissions page. Don't complain if you find that I end up deleting all your solutions to a particular problem in an effort to delete all the duplicates.

Migrated to Xen server

by bbi5291 on Oct 11, 2011 - 10:58:35 pm UTC
  • (0/0)
The Judge has been moved to a server with dedicated resources. Performance should now be better on all fronts (although some programs now take longer to execute; I'm looking into why this is).
This is costing me $28/month, so donations would be appreciated.
If you notice any issues, just mention them here.

Who wants problem setter and contest setter support?

by bbi5291 on Jun 24, 2011 - 11:00:03 pm UTC
  • (0/0)
I've decided that there's no immediate need to refactor the contest system as I had initially planned. I used to think the inefficiency of the database logic caused the poor performance of the site, and that it was fast sometimes because of caching. The actual truth is that all the slowness is due to occasional extremely high network latency, so nothing I do can guarantee that the site never takes 10 seconds to load (except moving to a dedicated server, which is actually too expensive).

I don't see any major issues with the Judge and I think it has all the piecen an online judge would be expected to have, with one exception --- support for non-admin problem setters and contest setters (as in SPOJ, which I consider the "industry standard", although we did have a comment system before they did, I think).

How many [non-admins] would like to become problem setters and contest setters, and how often do you see yourself adding problems?

After I add this functionality (if there is sufficient interest), I plan to basically stop active development on the Judge (barring some major breakthrough such as a significant expansion of the user base).

Migration complete

by bbi5291 on Jun 18, 2011 - 8:33:50 am UTC
  • (0/0)
The Judge has been moved to a new server.

If you notice anything strange over the next few weeks, let me know.

Note that this machine is slower than the previous one by a factor of about 1.3, so runtimes will differ accordingly.

Loss of data

by bbi5291 on Jun 06, 2011 - 5:56:56 pm UTC
  • (0/0)
Comment ratings from January onward have somehow been deleted. Sorry for the inconvenience.


by bbi5291 on Mar 27, 2011 - 3:44:30 am UTC
  • (0/0)
Recently, due to a performance bug, the Judge spent more than an hour trying to judge one submission. I have made some changes to prevent this from happening in the future, but if I have made any mistakes then some programs may be judged incorrect even when they are correct. If this happens then please make a note of it here and I'll fix it as soon as possible.

Session Expiry

by admin on Mar 03, 2011 - 5:27:34 pm UTC
  • (0/0)
Sessions should expire if user is inactive for 2-3 hours.
Joyce neglected to log off of Admin yesterday and when I opened my account on the same computer today, it was already logged in as Admin.