Computer Science Canada

DWITE December
Author:  Dan [ Mon Oct 01, 2007 4:01 am ]
Post subject:  DWITE December
The DWITE programing contest for high school students is holding there december round on December 12th, 2007.

For more info see http://dwite.org
Author:  HeavenAgain [ Sat Oct 13, 2007 11:47 am ]
Post subject:  Re: DWITE December
Confused just a few suggestion to the next few contest, after experiencing the first one. i think it will be nice if the contest could start at 3:10? or 3:15, becuase some school ends at 3:10 (like mine) so theres a disadvantage on the time, if we move it to a later time, im sure the team members can meet up and get ready
and another thing is, the examples of input and output, like the one on friday last problem, it will give us a better understanding of the problem if we were provided a "bigger maze", like some special cases, dead ends etc? Rolling Eyes not sure if you know what i mean, but it will be better if we were provided with a better example

but thanks for hosting this, it was REALLY fun Mr. Green
Author:  Tony [ Sat Oct 13, 2007 12:09 pm ]
Post subject:  Re: DWITE December
HeavenAgain @ Sat Oct 13, 2007 11:47 am wrote:
not sure if you know what i mean, but it will be better if we were provided with a better example

I know what you mean, though the "special cases" were in the starting distances (and locations) between the Velociraptor and the Human. A bigger maze would only delay the same result Wink

I'll look into providing either more samples, or follow up with some explanations.

I'm told that someone didn't understand the 4th Questions - Stacks of Blocks. Would drawing a diagram help?
Author:  McKenzie [ Wed Nov 14, 2007 8:57 am ]
Post subject:  Re: DWITE December
Diagrams almost always help.

Is there any way you can mail the questions to teachers 15-20 min before the contest starts so we can print them out for the students and hand them out as soon as the contest starts?
Author:  Dan [ Wed Nov 14, 2007 9:13 am ]
Post subject:  RE:DWITE December
This might be posible for the decmber contest however i do not think i can do it in time for todays.

Our e-mail program that can send mail to sefpiced user groups like teachers is still a bit buggy and untested and i whould not whont to risk breaking the site right befor the contest today.
Author:  Mr.S. [ Thu Nov 15, 2007 9:24 am ]
Post subject:  Re: DWITE December
That's a great idea about sending the questions to the teachers before the contest.

I noticed, in yesterday's contest, that my teams could not get access to the website and print off the questions until 10 or 15 minutes after the contest started. I'm assuming that this was because the website was trying to be accessed at the same time by the contest participants.

Excellent work with the new DWITE format. The website is easy to use and the contest questions are at level appropriate for high school students. Keep up the great work and looking forward to December DWITE.

Mr.S.

McKenzie @ Wed Nov 14, 2007 8:57 am wrote:
Diagrams almost always help.

Is there any way you can mail the questions to teachers 15-20 min before the contest starts so we can print them out for the students and hand them out as soon as the contest starts?
Author:  Martin [ Thu Nov 15, 2007 1:58 pm ]
Post subject:  RE:DWITE December
If anyone has any feedback on the questions (too hard? too easy?), post away.
Author:  Dan [ Thu Nov 15, 2007 8:03 pm ]
Post subject:  Re: DWITE December
Mr.S. @ 15th November 2007, 9:24 am wrote:

I noticed, in yesterday's contest, that my teams could not get access to the website and print off the questions until 10 or 15 minutes after the contest started. I'm assuming that this was because the website was trying to be accessed at the same time by the contest participants.


You whould be right, we had an intresting phomeon of teams rapidealy resreshing the site as the contest started (i am assuming this is to see if the contestcp has opened up the contest yet or not). This creasted a masive load on the server that lagged all requests. We have a few ideas to fix this like puting in a javascript clock that will say when the contest is going to start exctaly and maybe even refresh the site for them once it hits 0 (the idea is if they can see when the contest will start there will be no need to rapidealy refresesh the contestcp).

Also there may be server side things we can do to make the site more effeshent and i could do some tests to see if adding more mongrel clusters whould help or not. The server toped out at a 1 min load average of 45 and there was lots of bandwith left so i think the bottoel neck might just be how many mongrel process are running to server all the requests.

Sending the questions to teachers befor hand so they can print them out whould also reduce this starting load and whould not be as damging to the teams if they can not get on right away.

If all eltes fails i could allways look in to upgrading the server to the next level our datacenter offers.
Author:  Tony [ Thu Nov 15, 2007 9:36 pm ]
Post subject:  RE:DWITE December
I think we might have a couple of shared-hosting accounts available on the side. I've got that one with Textdrive and I don't remember when our Dreamhost account expires. We could potentially offload some requests there.. at least for the static content.
Author:  HeavenAgain [ Thu Nov 15, 2007 9:52 pm ]
Post subject:  RE:DWITE December
free marks FTW!!
If you just output the example's output, you could end up with 1 or more right solutions, so without any work , and just printing the answers to a file, hmmm
should that be changed or not.... or jsut twist the input case a little...
and checking if anyone is cheating? more than the number of teams in a school that is accessing the dwite page? (after all, only 1 computer per team is allowed right?)

and is it possibile to finish all 5 questions and get perfect in less than 30 mins? Confused
Author:  Dan [ Thu Nov 15, 2007 10:16 pm ]
Post subject:  RE:DWITE December
I did check the logs for the top 3 teams and they all had vaild submisons.

I can not tell if they had more then one computer or not and i never will fully be able to. That is why you are also sposted to have a teacher watching you.

As for hard coding the output, you might get 1 case right if you are lucky but there is no garuite that the test case is anything like the example. So you might end up with 20 "free" points but you deftaly are not going to be a high scoring team overall.

The top teams finshed closer to 1 hour, not 30 mins.

As for the posiblity of cheating by outputing the test case so the judge reports it back to you, we have a plan to fix this for the next contest but i do not think i will say how as it will be funner to mess up teams that try to cheat Wink. Also i am consdering increasing the bounces for geting it right the 1st try. Tho as i side i checked the top 3 teams and they did not do anything agisted the rules that i could see. For the most part they only submited 1 soultion for each problem witch is impersive.

There realy is no point in cheating or trying to hack the site as it is ment to be for parctise for other contests like the CCC so you are only hurting your self if you do.
Author:  thenewme91 [ Wed Nov 28, 2007 6:50 pm ]
Post subject:  Re: DWITE December
I know it's late, but one thing I'd like to suggest is some sort of optimized pseudo-server-side clock.

The internal clocks on the computers at my school are off by massive amounts. (Sometimes they're around an hour off -- so when it's 3:10 PM the clock may read, e.g. 4:20 PM, while the machine next to it might say 3:55 PM.) Plain Javascript won't work -- we find that the current "time remaining" counters are useless for us and we need to keep track of time ourselves.

The only way around this at the moment is to refresh the pages, because there is no way of determining the current time on the sever. We do try to be kind by ensuring only one user is refreshing the page, and that he only does it once every few seconds -- they print out copies for all teams, which stand around the printer waiting for copies to come out.

I'd recommend sending the current server time to e.g. a java applet or javascript, which will calculate the offset from the system clock and ensure that offset is accounted for in all time calculations. Otherwise, we will be hindered by any time-based access controls that rely on the local clock to be correctly set.

Failing that, one could use a static page that displays the current time (and only that time) as stated by the server, similar to what is available at e.g. time.gov. The load should be less than generating the entire contest page, at the very least.

Just my two cents.
Author:  Dan [ Wed Nov 28, 2007 11:29 pm ]
Post subject:  RE:DWITE December
We acuatly allready have the code to genearte the time remaing server side however i replaced it with the javascript version to stop peoleop from resreashing so much as it can overload the server if to many teams refresh like crazy.

It should be noted that the javascript time display does not control your access to the ContestCP so even if you school clock is set wrong you should still be able to access the page for the right amount of time (just not see how long you have left correctly).

What i might be able to do (not garutited for the decmenber contest) is make an option in the team setings to use a javascript counter or a static one. Or i could put both a static time and the javascript one.

Syncing the javascript clock might be posible as well, this aucatly is an intresting idea that i should expoler. AJAX could also be used as it whould only need to request a line from the server every x amount of time.

Also our server is syniced with offical time singals so it should be the same as what time.gov says :p
Author:  rahzab [ Fri Nov 30, 2007 11:43 am ]
Post subject:  Re: DWITE December
hey guys if the contest is after school i cant go...
so how do i sign out of the contest do i just tell my group team member?
Author:  Dan [ Fri Nov 30, 2007 11:48 am ]
Post subject:  Re: DWITE December
rahzab @ 30th November 2007, 11:43 am wrote:
hey guys if the contest is after school i cant go...
so how do i sign out of the contest do i just tell my group team member?


Your team leader (the person who made your team) can remove you from there team if they like. There is no rule saying you have to be there if you are on the team roster tho.

Also your teacher (if they have signed up for a teacher account) can remove you from a team roster.

Right now there is no way for a team to quit a contest as a hole.
Author:  rahzab [ Sat Dec 01, 2007 5:06 pm ]
Post subject:  Re: DWITE December
alright thanks!
Author:  StealthArcher [ Sat Dec 01, 2007 5:35 pm ]
Post subject:  RE:DWITE December
Is there any place I can get some practice questions?
Author:  Nick [ Sat Dec 01, 2007 5:42 pm ]
Post subject:  RE:DWITE December
on the dwite site look at older contests and they should have the questions posted with some sample input

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