Tomorrow, we have JOI Open Contest 2015 .

This is OI-like contest on CMS and prepared by Japan to practice IOI.

There are two rounds using same problems. You can participate whichever you want.

The first round is 04:00~09:00 GMT June 14, and second round is 10:00~15:00 GMT on same day. And since the server will be open until 14:00 GMT June 15, you can practice this round at any time until then.

Please don't talk about problems until second round will be over. I'm looking forward to see a lot of IOI-er and programming contest lovers at this contest!

UPD1: Contests has been over. It is free to talk about the problems from now. You can still practice until the server will be closed.

Could you give links on timeanddate.com, It will be easier to check time.

UPD: Links: Round 1, Round 2Expected difficulty?

JOI provides past problem for their open contests.

2012 : http://joiopen2012.contest.atcoder.jp/

2013 : http://cms.ioi-jp.org/open-2013/index.html

2014 : http://cms.ioi-jp.org/open-2014/index.html

In my opinion, their contests are one of the world's hardest OI-style competition :)

Difficulty of IOI is expected, but sometimes there is too hard problem like "synchronization" in 2013.

Where is the Registration link?

http://cms.ioi-jp.org/contest/ push the "登録" button and input your username, and first name, and last name. password will be automatically generated.

Thanks! :D

Site seems to be down. Can anybody upload statements somewhere?

It's fixed now.

I have submitted my output a few mintes ago but it's still evaluating :((

Me too, I'm waiting for 6 minutes now, it's still evaluating. Did you finally got an answer ?

Yes. But you should wait for about 15 minutes :((

OK, thanks !

The evaluation is taking more than 20 minutes on the last problem... Is everything ok?

Auto comment: topic has been updated by DEGwer (previous revision, new revision, compare).where is contest #1's results?

Good and hard contest, thanks a lot! Is there any editorial of the problems? :)

Could you please upload somewhere an archive with all tests for the tasks?

Anybody could submit the solutions and/or explanation? Because we can only test our solutions the next 19 hours and I think that I couldn't code them without reading them as I am still learning and very far away from this kind of contests

cheers!

Could you publish the final standings of the contest?

Anyone solved the last problem by converting given numbers. Into base k — except when k is one — and using a segment tree?

Pretty much! My solution is technically very similar, although I reasoned differently: since every dish contains at most 10

^{9}cells, then, if we use the spray on it at least 32 times, it is guaranteed to become empty. Therefore, I could store answers to the question "what the sum on this segment would be afteriapplications of the spray" for 0 ≤i≤ 32 in every node of my segment tree.Alex_2oo8 proposed another interesting solution using a segment tree: using the same observation, we observe that, if we don't apply the spray to empty dishes, then, without any updates, we can have 32 ×

Napplications of the spray at most, and each update adds at most 32 additional applications. Therefore, we can actually apply the spray to dishes one-by-one, and the only problem is finding the non-empty dishes quickly, which is easily accomplished by a segment tree. This solution wouldn't work if we were allowed to update the number of cells in a segment of dishes at once, but I imagine that it was easier to implement.I think our solutions r really close yeah but yours is so simpler and the second solution is interesting :DThnx for sharing

I was using a sqrt decomposition. Each value can be mapped by using a map(in c++) or some other data structures.For each dividing query(spraying query), we spray to every dish which isn't empty(that is whose value is positive number). I think this solution is similar to Alex_2oo8's solution,but I was using a sqrt decomposition instead of a segment tree for finding the non-empty dishes and spraying to them.

What is the expected solution of the second task (Election Campaign)? I solved it in O((N+M) log N), but I'm curious to know whether there is a linear or simpler solution.

How could we reach the problem statements and practice with them? I logged in to the system and it said the contest has ended.

:D

Could you upload the statements (if it's possible, test data as well) to somewhere?

How to solve election campaign ?