OJ Board

Last Sunday I participated on Mexico and Central America ACM competition. One of the problems was exactly the same as one of the UVA. Actually the only difference was the name and the first paragraph. The sample input and output were the same (also the format). I think this is unfair because if some team has solved this problem they have extra advantage.

I would like to know if there is a rule that states that the problems have to be new ones?

Is this situation common in other regions?

Do you think this is fair?

There is no specific rule that problems has to be new. It is common sense.

But now with so many programming problems it is difficult to keep the problemset new. Because it is impossible to remember about all problems solved and also problemsetters do not always solve many problems. If the problem test was an exact copy from UVa then you could complain. This year in Dhaka regional one problem was very similar to an UVa problem which I discovered later. Most regionals have 1/2 problems very similar to UVa.

oh... I think it is very unfair. But I understand that making new problem is very difficult.

I have participated on Asia regional acm/icpc, and all problems are very unique fo me. Because of that almost we know www online judge like uva or pku, if same problem would be on test, many teams can solve that problem very immediately, I think.

akercito, If you can, please tell me the uva problem which tested on the real contest. I'm very interested in that.

Shahriar Manzoor wrote: This year in Dhaka regional one problem was very similar to an UVa problem which I discovered later

hmm.. can u please name the problem you are talking about?
thanks.

I won't tell that here (Which problem was similar) . It is an excercise for you. Since u have solved so many problems and still don't know then it was fare I think.

And similar does not mean same. There statement and sample IO is completely different. It turned out that they actually have the same solving method. That is why I was disappointed as I wanted to set a high standard.

Actually about similar problems the real thing is intent. If the judges try their best and still there is some same problem that is a different thing, in Dhaka regional we tried our best to keep the problems new.

But if some regional copies problems from UVa that will be very unfair.

The problem is http://acm.uva.es/p/v101/10116.html and it is really a copy paste what we seen in the contest. We have complained about this situation and we are expecting an answer.

Could someone give us some advise?

Thanks a lot

thanks akercito, if what you say is true, I think you should report this issue to acm. but I can't believe ... mmmm

There was a similar incident in WF 2001 where a problem was exactly similar to a UVa problem. Many people complained but the rank did not change for this complain. After this incident ICPC applied restrictions on materials. Now in World Finals only a certain pages of documents are allowed. In early days it was unlimited.

You may get a reply but I assume that the rank will not change. As their is no logical solution for it. For example when there is error in judge data there is no 100% fair solution because it is hard to imagine what would have happened if the error was not there. Similarly it is hard to imagine what would have happened if this problem was not a copy. Also the rule of ICPC is "No extra place will be allowed to World Finals against an Appeal", that is if some team feels that they misses out world finals for this copy problem they will probably not get a place for this mistake. Because one cannot increase the penalty of another team just because it is assumed that they copied the solution during contest.

Whatever happens keep us updated about the outcome.

S M wrote: I won't tell that here (Which problem was similar) . It is an excercise for you. Since u have solved so many problems and still don't know then it was fare I think.

Hmmm...

Then I guess it must be one of the problems that I haven't solved in UVa.
To me, all the dhaka site problems seems to be new.

A - no
B - no
C - no
D - no
E - no
F - no
G - no
H - may be
I - may be
J - may be

I guess I have now got a major assignment in my hand.

I guess you have better assignments to do. So

http://online-judge.uva.es/p/v8/855.html

This is the similar problem.

Problem B of Dhaka regional was also very similar to a Andrew Stankevich contest problem at ZJU.

As I said it is difficult to avoid similarity. But some similarity is necessary to make the problemset easy and rankable (That can rank teams). It is better than filling the problemset with very hard ones, specially in a regional or national contest it cannot (should not) be done. We can switch to that mode in non competitive (Whose rank has no tangible value) contests like warmups.

Also I prefer to keep the problem statement of most problems short, that helps to avoid ambiguous statements. At least some problem statements should be short to make it interesting. Too many long problems and trappy problems increases the chance of accidents. But in this process the problemset was solved well before 5 hours, some long trappy problems could have made it impossible.

Some regionals have problems that are three pages long (without figures) which is pathetic. Also the presence of dirrerent types of problems DP, search, graph, greedy, geometry is necessary.

By identifying similar problems I don't want to undermine the problemsetters of Dhaka regional, they did a great job. I hope to get helps from them in future as well.