Computer Science Canada

DWITE Issues
Author:  A.J [ Thu Feb 19, 2009 7:03 pm ]
Post subject:  DWITE Issues
The questions this DWITE were good, but the actual testcases weren't good.

For #5, for some reason, they said that there would be at most 10 edges, and none of the testcases even come close to that!!

And all of the 'x' functions were : 1 + x/100

And, I still had my second submission to hand in, but the server crashed! I couldn't submit my 2nd submission for #5.!!

The testcases should have incorporated testcases where there were up to 10 edges with multiple different equation using 'x' (not necessarily 1 + x/100). All the teams in my school (seeing that the worst case was 10 edges) didnt code it, since a testcase with 10 edges and say about 2 equations (using 'x's) on each path from 'A' -> 'Z' is impossible to solve in the given time limit.

And how does one go about solving #4 ? The highest anyone got was 3/5 (although that could be just us not getting the intended solution)

I am kind of frustrated that #5's testcases were actually SO small, and very doable (much easier than what our school thought).
Author:  DanielG [ Thu Feb 19, 2009 7:08 pm ]
Post subject:  RE:DWITE Issues
very true, this is very similar to the final problem of the first dwite, where a simple heuristic guess was sufficient. for next year, dwite text case difficulty should reach that mentioned in the problems, and not allow those who attempt incorrect shortcuts (though correct for the sake of those test cases) to get full (or close to full) points.
Author:  chopperdudes [ Thu Feb 19, 2009 7:16 pm ]
Post subject:  RE:DWITE Issues
i've seen almost the exact question as number four, sadly, i didn't take note of the solution as at the time i probably didn't have the knowledge to understand it anyways.

i believe those who got 3/5 did so because of the time constraint. what i did, was find all possible permutations of the #'s, and find all the total distances for each permutation. but we also have a min variable to keep track of the minimum distance. so that we will not compute those permutations where during the process of permuting the distance is already greater than min.

i'm sure there is a "standard" way to do this type of problem (possibly dynamic programming), but i believe most who got 3/5 used brute force one way or the other.
Author:  Insectoid [ Thu Feb 19, 2009 7:18 pm ]
Post subject:  RE:DWITE Issues
And I wan't too please about being gimped a point in question 2...

nah, I'm kidding, I did read the notice.

lol, one of our 1-man teams submitted question 2, but had accidentally formatted the output with an extra space at the end of each word, resulting in 0/5, although he had the right answers.

It is rather annoying when the only real-time communication with Dan/Tony is via IRC, and my school has those ports blocked.
Author:  Dan [ Thu Feb 19, 2009 7:19 pm ]
Post subject:  Re: DWITE Issues
A.J @ 19th February 2009, 7:03 pm wrote:

For #5, for some reason, they said that there would be at most 10 edges, and none of the testcases even come close to that!!


The test cases where in the range of 1 to 10 edges as the question side they would be. Considering so few got theres working at all i don't think testing cases closer to 10 would do anything.


A.J @ 19th February 2009, 7:03 pm wrote:

And all of the 'x' functions were : 1 + x/100


Agian this is with in the sepcs of the question and again since so few got one working at all it did not effect the outcome.


A.J @ 19th February 2009, 7:03 pm wrote:

And, I still had my second submission to hand in, but the server crashed! I couldn't submit my 2nd submission for #5.!!


The server crashed exctaly when time ran out, it was due to the next contest not being found in the DB. So if you saw the error you where to late to submit it any way.

A.J @ 19th February 2009, 7:03 pm wrote:

The testcases should have incorporated testcases where there were up to 10 edges with multiple different equation using 'x' (not necessarily 1 + x/100). All the teams in my school (seeing that the worst case was 10 edges) didnt code it, since a testcase with 10 edges and say about 2 equations (using 'x's) on each path from 'A' -> 'Z' is impossible to solve in the given time limit.


Thats just silly. You just need one test case right to get points. Also this question was ment to be as hard as it souned, the test cases where just happened to be more lenient.


A.J @ 19th February 2009, 7:03 pm wrote:

And how does one go about solving #4 ? The highest anyone got was 3/5 (although that could be just us not getting the intended solution)


I still have to look in to this but it was desinged so it would be hard to get the last test cases as it would time out.


A.J @ 19th February 2009, 7:03 pm wrote:

I am kind of frustrated that #5's testcases were actually SO small, and very doable (much easier than what our school thought).


The idea of dwite is to wite a program that sovels the question not the test case, it's just hard to make the judge enforce that. Idealy it should have been has hard as your school thought however some teams got lucky in there asumption that they all where 1+x/100.
Author:  Dan [ Thu Feb 19, 2009 7:24 pm ]
Post subject:  Re: RE:DWITE Issues
DanielG @ 19th February 2009, 7:08 pm wrote:
very true, this is very similar to the final problem of the first dwite, where a simple heuristic guess was sufficient. for next year, dwite text case difficulty should reach that mentioned in the problems, and not allow those who attempt incorrect shortcuts (though correct for the sake of those test cases) to get full (or close to full) points.


Your doing it wrong if you are using shortcuts. DWITE is ment to be partice, if you cheat you are only cheating your self. Since the judge is an AI and not a real person there are limiations in being able to catch all short cuts. For example it is very hard to stop hardcoding witch just outputs a random number or peoleop acidentaly geting questions right. In this round the test cases where aucatly quite good at stoping hard coding and for question 5 the parsing of the weight on the edges of the graph was only a small part of the problem.


insectoid wrote:

It is rather annoying when the only real-time communication with Dan/Tony is via IRC, and my school has those ports blocked.


I am constaly watching my e-mail and my MSN and jabber is on during contests.
Author:  Insectoid [ Thu Feb 19, 2009 7:28 pm ]
Post subject:  RE:DWITE Issues
lol, I have to confess to submitting randomly generated answers. It is a contest, and my competitive nature forces me to eek out those few extra points at the last second.
Author:  SJ [ Thu Feb 19, 2009 7:44 pm ]
Post subject:  Re: DWITE Issues
for 5, i ended up randomly generating numbers too T.T

how difficult would you guys say #4 and #5 are? CCC stage1, stage2, or IOI?
Author:  chopperdudes [ Thu Feb 19, 2009 7:47 pm ]
Post subject:  RE:DWITE Issues
#4 would be stage 1, but should be in senior i'd say, maybe S5... that's because i've yet to seen brute force failing in junior lol.

#5 i'd say would be at least the stage 2, but for me, i would probably not be able to tell between a hard stage 2 question and an IOI question lol...
Author:  ecookman [ Thu Feb 19, 2009 7:55 pm ]
Post subject:  RE:DWITE Issues
i wish i actually had the time to participate in DWITE...it sounds fun
Author:  A.J [ Thu Feb 19, 2009 8:07 pm ]
Post subject:  Re: DWITE Issues
chopperdudes wrote:

#4 would be stage 1, but should be in senior i'd say, maybe S5... that's because i've yet to seen brute force failing in junior lol.

#5 i'd say would be at least the stage 2, but for me, i would probably not be able to tell between a hard stage 2 question and an IOI question lol...


are you kidding me?

#4 and #5 were easily #4 on stage 1 senior. They were actually quite easy.

You must notice that on CCC, they won't EVER give questions where they expect you to get a few of the testcases and not all of them Confused

so you really can't compare

and Dan, I really disagree with you about the server down time

it was down at least 4 minutes before the contest (i remember seeing the time left)
Author:  Dan [ Thu Feb 19, 2009 8:29 pm ]
Post subject:  Re: DWITE Issues
A.J @ 19th February 2009, 8:07 pm wrote:

and Dan, I really disagree with you about the server down time

it was down at least 4 minutes before the contest (i remember seeing the time left)


The time shown is based on your computers time, if you don't blive me look at the html and javascript source.

The cause of the crash was the next contest not being in the database and it only trys to load that when the contest is over.

I do have plans for fixing the clock so it is based on the server time, witch i hope to get in for next school year.
Author:  chopperdudes [ Thu Feb 19, 2009 8:46 pm ]
Post subject:  RE:DWITE Issues
how does one actually approaches #5?
Author:  A.J [ Thu Feb 19, 2009 8:50 pm ]
Post subject:  Re: DWITE Issues
chopperdudes wrote:

how does one actually approaches #5?


well, since dan's testcases were actually small, bruteforce would have worked. the people who got 5/5 on this assumed that the equations were always : a + x/b.....it was sooo rigged...oh well, at least 7th place overall isnt too bad...Sad
Author:  aoen [ Thu Feb 19, 2009 10:00 pm ]
Post subject:  RE:DWITE Issues
Question 4 was worded very poorly, our team only got 1/5 (when we likely would have gotten 5/5) because we thought that #..# had 2 units of wiring (a wire was placed on each of the 2 .'s), the first sample test case didn't clear up this ambiguity either (the answers assuming either the wires took up a square of space or wires are placed in between squares were identical). Lame :<. Our team wouldn't have moved up because of this, but still, how many people edit these questions -.-. Question 5 was flat-out too long, even the brute force approach required tons of code.

And as always bad test data is bad.
-The limits for the constraints question 5 weren't tested
-The question implied that the function for the time of each "path" could be pretty much anything (no brackets though), all of the text cases were in the form f(x)= a + b/x
-If such small constraints were going to be used for testing, how come the constraints on the actual question were so large, they indicated that brute force wouldn't work

I'm wondering, why is the test data always so... easy? Is it because larger test cases will lag the server XD?
Author:  A.J [ Thu Feb 19, 2009 10:04 pm ]
Post subject:  Re: DWITE Issues
aoen wrote:

Question 4 was worded very poorly, our team only got 1/5 (when we likely would have gotten 5/5) because we thought that #..# had 2 units of wiring (a wire was placed on each of the 2 .'s), the first sample test case didn't clear up this ambiguity either (the answers assuming either the wires took up a square of space or wires are placed in between squares were identical). Lame <. Our team wouldn't have moved up because of this, but still, how many people edit these questions -.-.

And as always bad test data is bad.
-The limits for the constraints question 5 weren't tested
-The question implied that the function for the time of each "path" could be pretty much anything (no brackets though), all of the text cases were in the form f(x)= a + b/x
-If such small constraints were going to be used for testing, how come the constraints on the actual question were so large, they indicated that brute force wouldn't work

I'm wondering, why is the test data always so... easy? Is it because larger test cases will lag the server XD?


I think the wording for #4 was pretty clear..you wanted to minimize the wiring that goes through all the computers....
However, I agree with you about the test data...but it isn't "as always bad test data is bad", it was only this time...

I thought the contest itself was good, so keep up the good work Dan and Tony Very Happy
Author:  Dan [ Fri Feb 20, 2009 1:49 am ]
Post subject:  Re: RE:DWITE Issues
aoen wrote:

Question 4 was worded very poorly, our team only got 1/5 (when we likely would have gotten 5/5) because we thought that #..# had 2 units of wiring (a wire was placed on each of the 2 .'s), the first sample test case didn't clear up this ambiguity either (the answers assuming either the wires took up a square of space or wires are placed in between squares were identical). Lame <. Our team wouldn't have moved up because of this, but still, how many people edit these questions -.-.


This is why we provied the samples. If you looked at them you would see that #..# could not have 2 units of wiring. In any case tho more editing of questions is allwasy good but it is hard to find peoleop who have the time to as well as no conflicts of intrest.

aoen @ 19th February 2009, 10:00 pm wrote:

Question 5 was flat-out too long, even the brute force approach required tons of code.


In past contests teams finshed the hole thing in 30mins, and we where getting complaints from some teams that it was to easy. Since this was the last round we thought we would throw somthing a bit diffrent, longer and harder then noraml. Next time maybe we will just try for diffrent and harder :p


aoen @ 19th February 2009, 10:00 pm wrote:

-If such small constraints were going to be used for testing, how come the constraints on the actual question were so large, they indicated that brute force wouldn't work.


I think you awnsered your own question there. We don't want brute force on this one, we wanted you to think about it :p

aoen @ 19th February 2009, 10:00 pm wrote:

I'm wondering, why is the test data always so... easy? Is it because larger test cases will lag the server XD?


I think the test data on question 4 was rather hard, if not too much so.

And yes, in some cases large test cases can lag the judge due to submsions getting stuck in inf loops, taking the maxiume time to run or hanging as the judge trys to kill them. However this is normaly not enought added time for us to worry about.


I do agree it would be better if the judge could stop burtforce and hardcoding and make sure students do the question the way it was ment however it's not allways easy to do or for see what students will do (creativity in awnsering questions can also be a good thing that we don't want to get ride of). Next season we will take a closer look into covering all the edge cases in test data (witch we noramly do) and cracking down on hard coding. I have deffentaly got your guys point about the test data and it will not be forgoten in feature rounds.
Author:  aoen [ Fri Feb 20, 2009 1:50 am ]
Post subject:  RE:DWITE Issues
Ya but HOW the wiring was placed on the grid wasn't really clearly explained Sad.

Regardless we still got 3rd Very Happy (mostly due to the fact that the questions were so impossible our heuristic algorithm that only covered one type of case beat most other teams XD)
Author:  phleet [ Fri Feb 20, 2009 2:50 pm ]
Post subject:  Re: DWITE Issues
Making a working solution for #4 wasn't all that difficult. All it required was a distant finder and permutation.

The distant between any two points on the grid was just

abs(y2-y1) + abs(x2-x1)

Since the path taken between the computers doesn't mater (wires can cross,can go under computers), only the distance between them matters.

I then built a table of all the distances (i.e. dists[2][7] would be the distance between computer 2 and 7 (which were located during the input reading), conversely dist[7][2] is the same.)

Next, we ran through all the permutations of the chains that could be formed. For instance, with 3 computers, the possible permutations are:

0 1 2
0 2 1
1 0 2
1 2 0
2 1 0
2 0 1

After our first submission, we realized the first number did not need to be permutated, since it causes duplicate checks (e.g. 0 1 2 is the same as 2 0 1), so there are only two possibly connection methods for 3 computers:

0 1 2
0 2 1

In terms of code itself, just look at ours (Team 0xDDDD). The function next_permutation() in C++ is godly in programming competition (singlehandedly got us 11th at ECOO CS finals last year).

What I'm interested in is a solution not involving permutations. The reason our solution did not get 5/5 was due to time constraints. In order to solve a 20 computer problem, 19 things must be permuted. This is 19! or 1.21645100408832 x 10^17 rearrangements of data. Not so fast.
Author:  saltpro15 [ Fri Feb 20, 2009 3:19 pm ]
Post subject:  RE:DWITE Issues
HOW TO EPIC FAIL AT DWITE:
step 1. rush to hand in Q1 and hand in the WRONG file, then hand it in again forgetting to change your test cases from for i : 1..3 to for i : 1..5
step 2. attempt an approximate solution to Q3, submit it twice by accident, then actually solve it perfectly 20 minutes later, only to realize you can't hand it in.
step 3. overthink Q4.
step 4. overthink Q5.
step 5. hand in your final question with 28 minutes left, only to have the judge not mark it in time and receive 0 points for it Sad

I would like to apologize to my teammate for performing so horribly this round, if it was not for him I wouldn't have got past Q2.


... I'm praying like crazy this doesn't happen again on the CCC ...
Author:  DanielG [ Fri Feb 20, 2009 4:53 pm ]
Post subject:  RE:DWITE Issues
number 4 is a harder version of the travelling salesman.... at least I think it is....
Author:  Dan [ Fri Feb 20, 2009 5:16 pm ]
Post subject:  Re: RE:DWITE Issues
saltpro15 @ 20th February 2009, 3:19 pm wrote:

step 5. hand in your final question with 28 minutes left, only to have the judge not mark it in time and receive 0 points for it.


The judge marks all questions that are handed in even if it is a second before the end. What can happen is you submit something and it does not get marked till after the contest is over and did not get to see it as marked even tho it was and your score was updated. Or in some cases it gets marked but gets the same or lower score then a first submission so your score stays the same.

For future rounds i plan on making it so teams can view a record of the judge's output and marking after the contest is over will additional information (such as the test cases used) that is not viewable during the contest.
Author:  SJ [ Fri Feb 20, 2009 5:29 pm ]
Post subject:  RE:DWITE Issues
in response to what phleet said, that was actually my first idea at #4, but realizing that it will time out (and being too used to topcoder) i didnt bother coding it at all and went to look for another algorithm.. which i didnt find, so my teammate ended up writing some greedy solution cuz we ran out of time... basically start with any 2 nodes tahts close to eachother, then try to add the next ones optimally. ended up getting only 2/5 Sad

anywho, i think a possible solution that'd do good on dwite (havent tested this) is to just do a dfs that greedily chooses what to process next, store the best result so far (to prune search tree), and check the running time everytime. if time runs out just output the best result so far.
Author:  saltpro15 [ Fri Feb 20, 2009 8:22 pm ]
Post subject:  RE:DWITE Issues
@SJ, my partner also attempted a greedy solution for Q4, netted us a measly 1/5 though Sad, although it's better than 0 i guess
Author:  DanielG [ Fri Feb 20, 2009 8:27 pm ]
Post subject:  RE:DWITE Issues
I also used a greedy approach (probably much like SJ's) and also got 2/5
Author:  saltpro15 [ Fri Feb 20, 2009 9:01 pm ]
Post subject:  RE:DWITE Issues
hell, another question like that and I'm using Rand.Int...
Author:  A.J [ Fri Feb 20, 2009 11:02 pm ]
Post subject:  Re: DWITE Issues
saltpro15 wrote:

hell, another question like that and I'm using Rand.Int...

Laughing don't, you did the right thing

and I did pretty much the same thing as daniel (not the algorithm, the bs'ing #4 part)
Author:  Syrith [ Fri Feb 20, 2009 11:58 pm ]
Post subject:  Re: DWITE Issues
I liked how the last few questions were hard to get points for just outputting a random number (only 4 teams got anything for Q5 and the solutions I've looked at that got 0/5 were pretty much just random output).

Edit:
Team The Right Way or the Wong Way's solution looks like they somehow cheated most of the answers.
http://dwite.org/uploads/vjdsbty4udejuu/87/59/1/E.java
Author:  Dan [ Sat Feb 21, 2009 7:53 am ]
Post subject:  Re: DWITE Issues
Syrith @ 20th February 2009, 11:58 pm wrote:

Team The Right Way or the Wong Way's solution looks like they somehow cheated most of the answers.
http://dwite.org/uploads/vjdsbty4udejuu/87/59/1/E.java


They deftly did cheat, tho i have to admit how they did it was some what creative. I will have to talk to tony about what to do about this.
Author:  saltpro15 [ Sat Feb 21, 2009 10:46 am ]
Post subject:  RE:DWITE Issues
If you cheat on DWITE you're really only cheating yourself, unless you REALLY REALLY REALLY want that book Razz
Author:  A.J [ Sat Feb 21, 2009 10:55 am ]
Post subject:  Re: DWITE Issues
how on earth did they know the answers ??????????? Burn Nuty Eyes
Author:  corriep [ Sat Feb 21, 2009 11:31 am ]
Post subject:  Re: RE:DWITE Issues
saltpro15 @ Fri Feb 20, 2009 3:19 pm wrote:
I would like to apologize to my teammate for performing so horribly this round,


AHEM!

Evil or Very Mad
Author:  Dan [ Sat Feb 21, 2009 2:16 pm ]
Post subject:  Re: DWITE Issues
A.J @ 21st February 2009, 10:55 am wrote:
how on earth did they know the answers ??????????? Burn Nuty Eyes


They found an expolite in the judge that would make it dump the input back to them. I am not going to go in to more detail intill i fix the issue.
Author:  saltpro15 [ Sat Feb 21, 2009 4:37 pm ]
Post subject:  Re: RE:DWITE Issues
corriep @ Sat Feb 21, 2009 wrote:
saltpro15 @ Fri Feb 20, 2009 3:19 pm wrote:
I would like to apologize to my teammate for performing so horribly this round,


AHEM!

Evil or Very Mad


yeah I sucked, sorry paul, I'll do better next time, promise Razz
Author:  zero-impact [ Sat Feb 21, 2009 9:38 pm ]
Post subject:  Re: RE:DWITE Issues
saltpro15 @ Sat Feb 21, 2009 10:46 am wrote:
If you cheat on DWITE you're really only cheating yourself, unless you REALLY REALLY REALLY want that book Razz


You must REALLY REALLY REALLY want that book then... Rolling Eyes
Author:  saltpro15 [ Sat Feb 21, 2009 9:39 pm ]
Post subject:  RE:DWITE Issues
oh zero-impact you're just jealous we beat you two times in a row now Wink lol jk
Author:  A.J [ Sat Feb 21, 2009 11:46 pm ]
Post subject:  Re: DWITE Issues
Dan wrote:

A.J @ 21st February 2009, 10:55 am wrote:
how on earth did they know the answers ??????????? Burn Nuty Eyes


They found an expolite in the judge that would make it dump the input back to them. I am not going to go in to more detail intill i fix the issue.


Aren't they going to get penalized? I think it is only fair to the teams they beat due the marks they got...(namely everyone lower than 4th place by 89 points!!!....they would have ended up 40th is it wasn't for that question...)
Author:  Dan [ Sun Feb 22, 2009 2:39 am ]
Post subject:  Re: DWITE Issues
A.J @ 21st February 2009, 11:46 pm wrote:

Aren't they going to get penalized? I think it is only fair to the teams they beat due the marks they got...(namely everyone lower than 4th place by 89 points!!!....they would have ended up 40th is it wasn't for that question...)


Due to the way the rules are worded right now, it does not look like we can and fallow them. We do have plans to update the rules for next round to fix this loop hole (as well to try to fix the issue with the judge that allowed them to expolite it).
Author:  Syrith [ Sun Feb 22, 2009 10:02 am ]
Post subject:  Re: RE:DWITE Issues
aoen @ Fri Feb 20, 2009 1:50 am wrote:

Regardless we still got 3rd Very Happy (mostly due to the fact that the questions were so impossible our heuristic algorithm that only covered one type of case beat most other teams XD)


You got 3rd? My team got 3rd. Shocked
Author:  Syrith [ Sun Feb 22, 2009 10:04 am ]
Post subject:  Re: DWITE Issues
Dan @ Sun Feb 22, 2009 2:39 am wrote:
A.J @ 21st February 2009, 11:46 pm wrote:

Aren't they going to get penalized? I think it is only fair to the teams they beat due the marks they got...(namely everyone lower than 4th place by 89 points!!!....they would have ended up 40th is it wasn't for that question...)


Due to the way the rules are worded right now, it does not look like we can and fallow them. We do have plans to update the rules for next round to fix this loop hole (as well to try to fix the issue with the judge that allowed them to expolite it).


Could you contact their teacher about it?
Author:  A.J [ Sun Feb 22, 2009 11:16 am ]
Post subject:  Re: DWITE Issues
Dan wrote:

A.J @ 21st February 2009, 11:46 pm wrote:

Aren't they going to get penalized? I think it is only fair to the teams they beat due the marks they got...(namely everyone lower than 4th place by 89 points!!!....they would have ended up 40th is it wasn't for that question...)


Due to the way the rules are worded right now, it does not look like we can and fallow them. We do have plans to update the rules for next round to fix this loop hole (as well to try to fix the issue with the judge that allowed them to expolite it).


What? So they'll get away with it and remain 4th place instead of 40th!!! Now THAT's unfair
Author:  Saad [ Sun Feb 22, 2009 11:28 am ]
Post subject:  Re: DWITE Issues
A.J @ Sun Feb 22, 2009 11:16 am wrote:
Dan wrote:

A.J @ 21st February 2009, 11:46 pm wrote:

Aren't they going to get penalized? I think it is only fair to the teams they beat due the marks they got...(namely everyone lower than 4th place by 89 points!!!....they would have ended up 40th is it wasn't for that question...)


Due to the way the rules are worded right now, it does not look like we can and fallow them. We do have plans to update the rules for next round to fix this loop hole (as well to try to fix the issue with the judge that allowed them to expolite it).


What? So they'll get away with it and remain 4th place instead of 40th!!! Now THAT's unfair


No rules were in fact broken by what the team did.
Quote:
From the people category

3. Do not cheat. This is meant to be a practice competition.
- no consulting with non-team members in any manner
- no pre-written algorithms or code

This defines cheating as either consulting with other people that are not part of the team during the contest and as having pre-written code or algorithm. Based on the wording what the team did isn't breaking the rules. You may not agree with what they did but it doesn't change the fact that it is allowed.

Furthermore, if their marks were to be changed then it would be breaking the rule specified under the Problem Submission category.
Quote:
7. Decisions of Judge DWITE are final.
As changing the marks isn't allowed after the judge has marked it.

Rules can be found here.
Author:  A.J [ Sun Feb 22, 2009 11:38 am ]
Post subject:  Re: DWITE Issues
Saad, you of all people should know what they did was cheating...they got the input from their first submission, manually solved the testcases, and then output the specific answers to testcases on their second submission!

if that isn't cheating, I don't know what is!

And NO, they do not define what cheating is there. They just say "Don't cheat". The points there are other things not to do. IT is obvious that you aren't supposed to get the input from your 1st submission and utilize it on your second submission !!!!
Author:  Saad [ Sun Feb 22, 2009 11:52 am ]
Post subject:  Re: DWITE Issues
A.J @ Sun Feb 22, 2009 11:38 am wrote:
Saad, you of all people should know what they did was cheating...they got the input from their first submission, manually solved the testcases, and then output the specific answers to testcases on their second submission!

if that isn't cheating, I don't know what is!


It is irrelevant to care if I see it as cheating or what you consider cheating. What is important is whether the DWITE rules define it as cheating or not. Since the rules do not consider it cheating (see previous post) then the team's method was fair game.

A.J @ Sun Feb 22, 2009 11:38 am wrote:
And NO, they do not define what cheating is there. They just say "Don't cheat". The points there are other things not to do.


If it was another thing not to do then it would have been a different point on its own. Since it is a sub list, it means that it defines what cheating is which is like taking a general category and listing down points that help make it more specific.

A.J @ Sun Feb 22, 2009 11:38 am wrote:
IT is obvious that you aren't supposed to get the input from your 1st submission and utilize it on your second submission !!!!


Where are you getting this from? If it is based on your definition of cheating then it is irrelevant.
Author:  A.J [ Sun Feb 22, 2009 12:04 pm ]
Post subject:  Re: DWITE Issues
Saad wrote:

Where are you getting this from? If it is based on your definition of cheating then it is irrelevant.


Saad?!?! You serious?!?! That's not MY definition of cheating...it is just WRONG! Why don't you look at the testcases for CCC and then use them to output the desired output? It isn't on their RULES! But it is still considered cheating!!!
Author:  saltpro15 [ Sun Feb 22, 2009 12:20 pm ]
Post subject:  Re: DWITE Issues
Quote:

They found an exploit in the judge that would make it dump the input back to them. I am not going to go in to more detail until i fix the issue.


I call this cheating. submitting Rand.Int's is really more of a joke than cheating, as you really can't expect that to work, but I agree with A.J. the difference between 4th and 40th is too big to overlook because of a loophole
Author:  Saad [ Sun Feb 22, 2009 12:26 pm ]
Post subject:  Re: DWITE Issues
A.J wrote:
Saad?!?! You serious?!?! That's not MY definition of cheating...it is just WRONG!


Wrong, perhaps. Is it part of the DWITE definition? No.


A.J wrote:
Why don't you look at the testcases for CCC and then use them to output the desired output? It isn't on their RULES! But it is still considered cheating!!!


Why would it be considered cheating if it is not stated in the rules? According to who is it considered cheating? Can I see the rules for the CCC? Even if the CCC seems to have a different rule that accounts for this, why should it be applied to DWITE if it is not written in the DWITE rules?

Note: I am not trying to troll anyone, I am just trying to show that what they did was not cheating and they did not break the rules as a result of that.

Edit: Rewording for a few sentences.
Author:  Syrith [ Sun Feb 22, 2009 1:06 pm ]
Post subject:  RE:DWITE Issues
The sad part is, they FAILED one of the outputs.
Author:  A.J [ Sun Feb 22, 2009 1:51 pm ]
Post subject:  Re: DWITE Issues
Syrith wrote:

The sad part is, they FAILED one of the outputs.

yes, apparently they made a manual error while trying to bash out the 5th testcase...
Author:  DanielG [ Sun Feb 22, 2009 2:04 pm ]
Post subject:  RE:DWITE Issues
I don't think it's a manual error, more likely on purpose as to make it less noticeable. I could be wrong though.
Author:  saltpro15 [ Sun Feb 22, 2009 2:10 pm ]
Post subject:  RE:DWITE Issues
well, if loopholes like this are how DWITE is going to be from now on you might as well award first place to ever finds the most creative way to cheat. I propose holding Tony and Dan at gunpoint in my basement while the contest is going on. Very Happy anyone have a better idea?

(im jk btw, don't ban me)
Author:  A.J [ Sun Feb 22, 2009 2:11 pm ]
Post subject:  Re: DWITE Issues
DanielG wrote:

I don't think it's a manual error, more likely on purpose as to make it less noticeable. I could be wrong though.


I don't think so....he can't make it seem less noticeable, it is apparent to anyone who sees his code that he cheated.
Author:  DanielG [ Sun Feb 22, 2009 2:15 pm ]
Post subject:  Re: DWITE Issues
A.J wrote:

DanielG wrote:

I don't think it's a manual error, more likely on purpose as to make it less noticeable. I could be wrong though.


I don't think so....he can't make it seem less noticeable, it is apparent to anyone who sees his code that he cheated.

true, but if more people had solved it, it is less likely that someone would look at their code (due to preffering to look at 5/5 for the correct solution)
Author:  A.J [ Sun Feb 22, 2009 2:26 pm ]
Post subject:  Re: DWITE Issues
That's also true.

They were 4th place (and more noticeably one of the only ones who didn't get a 0 for #5), so it was kinda obvious.....

Daniel, we would have been tied 6th if it wasn't for them...

EDIT : fixed a few words
Author:  Tony [ Sun Feb 22, 2009 2:48 pm ]
Post subject:  RE:DWITE Issues
It was not the expected solution, but neither are solutions that write Rand.Ints or hard-code arbitrary answers in. Lets call this a particular solution, instead of a general solution. DWITE solutions come with heuristics, assumptions, guesses. We can't objectively control for all such factors, across all submissions, although over the last two seasons we've also been learning and tweaking the system to make it more of a challenge.

Some guys (I'm looking at you A.J.) need to chill and realize that the DWITE score (your absolute, and in relation to others) does not carry the same weight as CCC or ECOO do. It's supposed to be some practice; it's supposed to be fun.

The judge does have issues. On some occasions a solution that works locally might not behave as expected in judge's environment. That sucks. Though most teams take note of such gotchas and move on.

I appreciate your opinion and that this fact was brought up. Dan and I will take this as an opportunity to review the rules and the judging process. But fighting to decrease the score of another team is not really in the spirit of DWITE.
Author:  A.J [ Sun Feb 22, 2009 3:31 pm ]
Post subject:  Re: DWITE Issues
Tony wrote:

I appreciate your opinion and that this fact was brought up. Dan and I will take this as an opportunity to review the rules and the judging process. But fighting to decrease the score of another team is not really in the spirit of DWITE.


You are absolutely right Tony...I am sorry..please accept my humble apology Crying or Very sad

I do realize that this contest is a fun way to review for contests such as CCC and ECOO, and I apologize for acting soo competitive Sad

I would like to take this opportunity to thank Tony and Dan for another awesome season of DWITE. Keep up your good work, and thanks for everything Very Happy
Author:  bbi5291 [ Thu Feb 26, 2009 9:54 pm ]
Post subject:  Re: DWITE Issues
Did this exploit have anything to do with using an include statement to paste the test data into the source code?
Author:  Dan [ Thu Feb 26, 2009 10:38 pm ]
Post subject:  Re: DWITE Issues
bbi5291 @ 26th February 2009, 9:54 pm wrote:
Did this exploit have anything to do with using an include statement to paste the test data into the source code?


No, and i don't see how that could work....
Author:  McKenzie [ Fri Feb 27, 2009 6:17 pm ]
Post subject:  Re: DWITE Issues
First, let me say that Tony and Dan have done a fantastic job with DWITE. It was good when Mr. Sentjens started it, but it is GREAT now.

As far as cheating goes (and I think AJ's common sense definition is on the money) I understand why a team would want to ('hacking' Hacker Dan...cool) but I think a score of zero is the correct response. I know you see DWITE as "just a fun contest" to help prepare for CCC and ECOO but a lot of kids give their blood sweat and tears to DWITE and having a fake team in spot 4 means everyone else appears one rank lower. Don't kid yourselves, kids go home and say "hey, we got 11th place in DWITE"
Author:  BigBear [ Sun Mar 01, 2009 3:48 pm ]
Post subject:  RE:DWITE Issues
If they did not break the rules, what about the fact that they submitted 2 answers.
Author:  Tony [ Sun Mar 01, 2009 4:17 pm ]
Post subject:  RE:DWITE Issues
Every team gets two submissions for each problem. You'd be surprised how often someone reads or writes to a file with a wrong name.
Author:  saltpro15 [ Sun Mar 01, 2009 4:20 pm ]
Post subject:  RE:DWITE Issues
or submits the wrong question 2 times by accident... well, lesson learned I suppose
Author:  A.J [ Sun Mar 01, 2009 5:03 pm ]
Post subject:  Re: DWITE Issues
McKenzie wrote:

First, let me say that Tony and Dan have done a fantastic job with DWITE. It was good when Mr. Sentjens started it, but it is GREAT now.

As far as cheating goes (and I think AJ's common sense definition is on the money) I understand why a team would want to ('hacking' Hacker Dan...cool) but I think a score of zero is the correct response. I know you see DWITE as "just a fun contest" to help prepare for CCC and ECOO but a lot of kids give their blood sweat and tears to DWITE and having a fake team in spot 4 means everyone else appears one rank lower. Don't kid yourselves, kids go home and say "hey, we got 11th place in DWITE"


I agree. Our school did put a lot of effort into this contest and we were kind of disappointed to see that we all got a place lower than we would have because of this team.

I also agree that DWITE is a GREAT contest, and I am looking forward to whether they have a spring and summer contests.
Author:  saltpro15 [ Sun Mar 01, 2009 5:06 pm ]
Post subject:  RE:DWITE Issues
spring DWITE would be great, summer, not so much. well I wouldn't be in it at any rate Very Happy
Author:  saltpro15 [ Wed Mar 18, 2009 7:39 am ]
Post subject:  RE:DWITE Issues
... sooooo did anyone ever find an optimal way to solve Q4?
Author:  DemonWasp [ Wed Mar 18, 2009 9:33 am ]
Post subject:  RE:DWITE Issues
Wasn't problem 4 just a restatement of the Traveling Salesman Problem? In that case, the best you can do is a brute-force solution: compute the distance for each permutation, choose the smallest, output. There's no known faster way. For more information, see: Traveling Salesman Problem.
Author:  saltpro15 [ Wed Mar 18, 2009 11:07 am ]
Post subject:  RE:DWITE Issues
ah thanks DemonWasp Smile

so Dan and Tony please,

NO MORE OF THESE UNSOLVABLE PROBLEMS

(hope that tag worked)
Author:  DemonWasp [ Wed Mar 18, 2009 12:22 pm ]
Post subject:  RE:DWITE Issues
It's not technically unsolvable. The only difficult bit is determining the permutations without duplications, which minimises the number of cases you need to compute. After that, just optimise to do as well as possible - I think someone mentioned a while ago that it was fairly easy up to 19 nodes, it was only 20 that would take an unreasonable amount of time.
Author:  saltpro15 [ Wed Mar 18, 2009 12:24 pm ]
Post subject:  RE:DWITE Issues
So brute forcing would solve this in O(n!) time correct? I do not think there is any way a high school student could code a 5/5 solution in less than 3 hours
Author:  Analysis Mode [ Wed Mar 18, 2009 1:30 pm ]
Post subject:  Re: DWITE Issues
well, I guess we'll never know, as HAnson didn't participate in the last contest.
Author:  saltpro15 [ Wed Mar 18, 2009 2:40 pm ]
Post subject:  RE:DWITE Issues
haha true, this definitely would have been challenging for him though, it's challenging for anyone

EDIT:
I have an idea as to how to solve this 5/5! To Bluefish I go, let's hope I remember enough C++ to do this...
Author:  Foundation [ Wed Mar 18, 2009 8:27 pm ]
Post subject:  Re: DWITE Issues
I would be very interested to know how one would optimize going through permutations as that would be O(N!).

Another solution to P4 would be a standard application of the optimized TSP DP solution. Letting each state be represented as an integer representing all the nodes visited and an integer representing the current node.

Then the time complexity would become O(2^N*N) which is around 40 million and will work within the 3 second time limit.
Author:  saltpro15 [ Wed Mar 18, 2009 8:35 pm ]
Post subject:  RE:DWITE Issues
never mind, my idea has died Sad

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