Computer Science Canada

Cheating teams
Author:  jli1 [ Wed Jun 02, 2010 5:43 pm ]
Post subject:  Cheating teams
If you guys look at DWITE 7, the team Wonderbread hard coded all the answers. I'm not sure if this indicates they were the people who DDoS'd, but it seems weird. Also, AJ seems to have gotten all of the solutions pretty much instantly......

Whats with people hacking and cheating DWITE.. Its just a practise educational contest.
Author:  Insectoid [ Wed Jun 02, 2010 6:02 pm ]
Post subject:  RE:Cheating teams
AJ is a genius, he did it all legitimately. Trust me on that. Wonderbread is looking fishy though...
Author:  jli1 [ Wed Jun 02, 2010 6:20 pm ]
Post subject:  RE:Cheating teams
Yeah, sounds about right.
Author:  A.J [ Wed Jun 02, 2010 7:12 pm ]
Post subject:  RE:Cheating teams
How on earth did Wonderbread hardcode the values? Unless they have someone on the inside, I can't come up with any other way on how they could have done that (unless they had the program return the values somehow to their server...somehow).

As the dwite.org website was down till about 3:35 or so, our teacher (who got emailed the questions) showed us the questions when the contest was supposed to begin (as he received an email from Dan saying that he is to show the problem statements to us, the students, at 3:15 PM. Our teacher, in fact, waited for a while before actually showing it to us, as the website was down. Then he later showed it to us as he figured it was another attack on the website).

Hmm, but I am kind of curious to how Wonderbread became aware of the actual testdata.

@Insectoid- Thanks, I am flattered Very Happy
Author:  Insectoid [ Wed Jun 02, 2010 7:22 pm ]
Post subject:  RE:Cheating teams
One team did this before by having their code e-mail the test cases, which they then worked out manually and subsequently re-submitted the hardcoded answers (at least that's how I've interpreted what I've been told, details get lost in time). Still, that requires a second submission while Wonderbread got it all first try.
Author:  jcollins1991 [ Wed Jun 02, 2010 7:24 pm ]
Post subject:  Re: RE:Cheating teams
Insectoid @ Wed Jun 02, 2010 7:22 pm wrote:
One team did this before by having their code e-mail the test cases, which they then worked out manually and subsequently re-submitted the hardcoded answers (at least that's how I've interpreted what I've been told, details get lost in time). Still, that requires a second submission while Wonderbread got it all first try.


Have two teams ? One to get test data and another to submit ...
Author:  Insectoid [ Wed Jun 02, 2010 7:31 pm ]
Post subject:  Re: RE:Cheating teams
jcollins1991 @ Wed Jun 02, 2010 7:24 pm wrote:
Insectoid @ Wed Jun 02, 2010 7:22 pm wrote:
One team did this before by having their code e-mail the test cases, which they then worked out manually and subsequently re-submitted the hardcoded answers (at least that's how I've interpreted what I've been told, details get lost in time). Still, that requires a second submission while Wonderbread got it all first try.


Have two teams ? One to get test data and another to submit ...


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Author:  A.J [ Wed Jun 02, 2010 7:47 pm ]
Post subject:  RE:Cheating teams
However none of the other teams from the same school as Wonderbread even submitted a program for this round...
Author:  Amailer [ Wed Jun 02, 2010 7:53 pm ]
Post subject:  RE:Cheating teams
Pretty pathetic that people would cheat in this contest, even more pathetic that someone attacks the website...
Author:  TheGuardian001 [ Wed Jun 02, 2010 8:18 pm ]
Post subject:  Re: Cheating teams
It's possible they wrote a program to find the results, then submitted a program that would simply output the hardcoded results to save on processing time.
Author:  Dan [ Wed Jun 02, 2010 8:36 pm ]
Post subject:  RE:Cheating teams
I am pretty sure i know how they did it and it is no where near advanced as you guys are giving them credit for.

They will be dealt with. However i first need to investigate more and contact there teacher.
Author:  jli1 [ Thu Jun 03, 2010 12:13 pm ]
Post subject:  Re: RE:Cheating teams
A.J @ Wed Jun 02, 2010 7:47 pm wrote:
However none of the other teams from the same school as Wonderbread even submitted a program for this round...


When you sign up, you can choose any school, so they could have just used some random one.
Author:  A.J [ Thu Jun 03, 2010 4:09 pm ]
Post subject:  RE:Cheating teams
Hmm...I am curious to know how they managed it. Well, I guess it doesn't matter as long as Dan can find a way around it.
Author:  Unnamed.t [ Thu Jun 03, 2010 5:01 pm ]
Post subject:  Re: Cheating teams
AJ, I agree with Insectoid, you are a genius Smile But what me and my team assumed was that you submitted the problems instantly because you already had them programmed. The problems in this DWITE were the same as the ones in the previous DWITE round 7. And I recall you talking about them in another thread. I still think that you are fully capable of doing all the problems that fast (except prob 4 THAT WAS HARD).

I have another question as well, how come I can't use a link to download your code? and what language do you program in?
Author:  A.J [ Thu Jun 03, 2010 7:14 pm ]
Post subject:  RE:Cheating teams
Well, you are right in assuming that I did see the problems before, as I did see a few them before hand (mainly because my teacher showed them to us before the site came back on). Even though I was able to code #1/#2/#3/#5 fairly quickly, #4 was the annoying one. I used Turing for #4, but I confess that I did predict that a bedmas question would be on and that probably gave me an advantage (as I have coded such calculators in the past, and as I had lost my USB a few days prior to DWITE, I was busy re-coding some programs I had lost, like an 8 puzzle solver, a connect 4 AI and a bedmas calculator...talk about good luck sprouting out of bad luck). Though I thank you for your compliment, Unnamed.t Very Happy

EDIT: Also, I have noticed that team 'Wonderbread' has now been stripped of their points from the last round.
Author:  Shanethe13 [ Thu Jun 03, 2010 10:10 pm ]
Post subject:  RE:Cheating teams
I guess I got really lucky with question 4. Literally a week or two ago I wrote my own graphing calculator, using my own variation of the Shunting Yard algorithm. I had spent so many hours refining it, that I simply had to code from memory when I saw problem 4 Razz
Author:  Unnamed.t [ Fri Jun 04, 2010 4:54 pm ]
Post subject:  Re: Cheating teams
A.J wrote:
#4 was the annoying one. I used Turing for #4, but I confess that I did predict that a bedmas question would be on and that probably gave me an advantage


Wowwww, I'm going to admit, it is pretty hard doing something like problem 4 inside Turing. I saw a reasonable solution in Java and started to rip my hair off (not literally) on why I hadn't used simplification methods in the program (e.g. replacing - with +- and " " with ""). I spent about 30 minutes trying to make a program but totally gave up. And just to know, other than Turing, what other languages do you use for DWITE competitions?
Author:  A.J [ Fri Jun 04, 2010 9:13 pm ]
Post subject:  RE:Cheating teams
Oh, I mostly always code in C++. I occasionally use Turing for certain questions (though I should stop doing that...). I can PM you my programs from the past DWITE if you want.
Author:  Unnamed.t [ Fri Jun 04, 2010 10:11 pm ]
Post subject:  Re: Cheating teams
Oh no no that's alright. I just wanted to see the programming capability of the language you use (the fact that it brought you in first place twice) Personally I would argue that Python actually fits best in the Dwite programming competition. The speed of Python in a good IDE is like the speed of a mclaren F1. Usually The first two problems of DWITE are always about speed.
Author:  A.J [ Fri Jun 04, 2010 11:33 pm ]
Post subject:  RE:Cheating teams
Well, I personally feel that all the questions on DWITE are about speed. Usually, the questions are trivial algorithmically, so speed (and good luck) determines the top few spots. I include good luck, as I know of some teams whom have submitted solutions to the wrong questions, regardless of being on of the first teams to submit a solution.

I am just happy that for once in all of my highschool life I actually managed to do well in a contest (1st place overall for this DWITE season Very Happy). Those who know me know that I usually perform poorly in contests even though I usually don't lack the knowledge required to do well.
Author:  Shanethe13 [ Sat Jun 05, 2010 11:43 am ]
Post subject:  Re: RE:Cheating teams
A.J @ Fri Jun 04, 2010 11:33 pm wrote:
I am just happy that for once in all of my highschool life I actually managed to do well in a contest (1st place overall for this DWITE season Very Happy). Those who know me know that I usually perform poorly in contests even though I usually don't lack the knowledge required to do well.


Well, congratulations! If this season is anything to go by, you definitely do know what you're doing Razz
Author:  Unnamed.t [ Sat Jun 05, 2010 11:51 am ]
Post subject:  Re: Cheating teams
You've got a pretty good point in saying that every problem is about speed. I guess that is up to your mathematical ability. Most of the time, problems 3 and 5 need a lot of thinking or "figure outing". This just goes to show that these competitions are about math just as much as programming.

Oh yeah, I forgot to ask, is there a setting you put on your dwite team to stop your code to be downloaded or is it something else? I'm not asking to see your code I just want to know if I'm able to do the same thing as to stop people from dowloading my code.
Author:  A.J [ Sat Jun 05, 2010 1:27 pm ]
Post subject:  RE:Cheating teams
oh...right, I forgot to turn that off. Basically, at the TeamCP page click "Edit profile and roster", and at the bottom of your profile description there should be a checkbox "Show Team's Code For Past Contests:".

Well, I don't think it is much of mathematical ability as it is algorithmic knowledge that helps. If you have a basic understanding of some fundamental algorithms (such as determining the shortest path between two points on a graph) and if you can code them with sufficient speed, then you should be good. I should also mention that a lot of the questions (well, not a lot, but some) on DWITE tend to be ad hoc (as in you have to come up with an algorithm that suits the question). For these type of questions, I believe that it just comes down to speed (and maybe experience).
Author:  Unnamed.t [ Sat Jun 05, 2010 4:45 pm ]
Post subject:  Re: Cheating teams
Right I totally agree with you. You just need the write experience with algorithms and be able to understand the question properly. Like which questions need recursion, which question needs an ASCII string function etc. Yeah and Thanks a lot for showing me how to change the settings for the ability to show ur code.
Author:  A.J [ Sat Jun 05, 2010 5:19 pm ]
Post subject:  RE:Cheating teams
Hey, no problem. I have been giving this talk to newcomers to our CS club for 2 years now Smile
Author:  chili5 [ Sat Jun 05, 2010 5:35 pm ]
Post subject:  RE:Cheating teams
Hey, AJ any chance you can explain #4? Smile It was the only one that I had no idea how to approach. Well the weird thing is I got perfect on #1 and hardly understood what it was asking.

Then #5 was odd... got 5/5 but I still don't get it. I just checked if k % 2 = 0 or not. I dunno what told me to try that but it got perfect.

So really the only questions I actually understood how to do was 2 and 3.
Author:  A.J [ Sat Jun 05, 2010 8:09 pm ]
Post subject:  Re: Cheating teams
Sure, I'll briefly explain the solutions to the problem set:

#1 - Basically, they are asking you for the xth significant bit of the binary representation of a number y. I believe the shortest way of doing it would be:

c++:

cout << (((1<<y)&x)==(1<<y)) << endl;
//basically performs the bitwise 'and' operation on 1 followed by y 0's and the number x. If it is a 1, it should return 1 followed by y 0's. Otherwise, it is a 0.


#2 - Trivially checking for primes using the 'check up to sqrt' method works in time.

#3 - Performing a floodfill at point 'A' after changing it to an oil '#' suffices.

#4 - Now for this problem, it is just one big recursive (or iterative) function. Following the rules of BEDMAS and some ad hoc optimizations (which is not necessary for this problem at all, but efficiency does help) you can code it up. The use of stacks is quite helpful for this problem. I believe team 'Kuro's solution is quite compact, if you want an example. My code, on the other hand, rambles on and on, so I rather not use it as an example. Basically looking initially for matching brackets and evaluating the expression inside them following the order of operations is your safest bet. I am sorry that I couldn't be of more help, as one can only learn by looking at examples (being an ad hoc problem, examples do help quite a bit).

#5 - I guess the added story masks the simplicity of this problem. If we were to represent the snappers' state as a giant binary number (with '1' being on and '0' being off), realizing that snapping one's fingers is equivalent to adding 1 to this binary number is the essence of this problem (try working with a few examples to see what I am saying). From here it is easy to see that basically the answer is ON iff (with two f's!) the rightmost N bits of K are 1. @chili5 I guess you got lucky with assuming that k%2 works, as all the input values with an odd 'k' was one less than a power of 2, making the rightmost N bits 1's Smile. But you were right in assuming that k can't be even.

I hope this cleared up any confusion Smile

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