Greetings everyone!
Last year I didn't qualify for the Junior Balkan Olympiad in Informatics, but this year I think I have a real chance to participate there. In fact I'm second in the team for now.
I want to ask about who else is going to participate. Also I'm curious about where and when JBOI 2016 will be held, because as far as I remember last year it was announced that it will be Macedonia 2 months before the event.
I think it's to early for this question to be answered. I personally think this year it could be in Cyprus (like BOI 2016) or again Bulgaria might try organizing it. But still I think it's too early for this question. Also I want to note that in most countries which will participate in JBOI the team selection hasn't even began. I would expect something new to be known in late april/may.
I got information that it will be held in Macedonia again. Can s.o. tell if this is true or not?
If there will be in macedonia again then good luck without feedback,considering last year...(the contests without feedback are very shitty).
constests without feedback are very fun
I wish you not to have JBOI in Macedonia. Last year I went to Ohrid. The city and the lake were awesome but the contest was not good in my opinion. The place it was held in had a lot of cables, you could hardly walk inside the room and they said that if you unintentionally unplug some cable, you will be disqualified. We had to work under Windows and Codeblocks was the only editor available. There was no feedback at all, moreover we had a marathon problem where you get points based on how good your solution is compared to the others without feedback...
PS: Good luck :D
And i waited 2 hours to go to restroom and lost ~100 points because of < instead of < = ,not the best experience!
Yeah, I also lost 100 points because of "&" instead of "|" since I was doing some things with masks, another 35 points because of cin/cout instead of scanf/printf (I used the magic lines but there was no feedback) and another 40 points because of a resubmit in the last 10 seconds of the first day (from 74 to 34 on the 'marathon' task) :(
That's hard to hear (being one of the organizers), but it happened (the no-feedback part) because we had very little time to prepare and organize the Olympiad. Organizing something like that in 2 weeks (how much time we had for tasks, tests, contest system) is practically impossible, and doing it without any major issues like wrong tests and stuff was the main point for us. We also considered doing feedback, but there was very little time for testing.
Don't worry, no one was disqualified for stepping on a cable or something like that — someone did it during the Practice phase I believe, and I guess they decided to warn contestants to be a bit more cautious.
Btw. If it's organized in Macedonia this year, I'm sure there will be feedback. I'm pretty confident that JBOI will NOT be held in Macedonia though — something should have come up by now.
There can't be equal condition without feedback,it became a competition of type "who write the correct solution from the first",the single thing it needed was feedback and that all to make it perfect.
I liked Serbia because there was ioi evaluating system.
Do you know where JBOI will be?
To be honest, no. I have no idea where JBOI 2016 will be held. I'll try to ask though and let you know.
I_Love_Tina The whole problem is that some countries refuse to host JBOI pretty late, and then some other country needs to jump in and organize the contest in a short amount of time. However, There was a meeting about feedback (during or after JBOI 2015) where they actually explicitly stated that the next Olympiads should/must have feedback so ... that's a good thing then. :)
Maybe you're right,organising a contest is a big deal,but try to undestand me if i just wouldn't solve the problem it would be okay but there was just a character between me and gold.
Now I wonder If I really want to go to JBOI. But JBOI being held in Macedonia is just a rumor. I want to know where it will be held for sure. If you have any info please contact me!
As a lot of people asked me abount were was my info from (the information that JBOI will be held in Macedonia) I wanted to say that it was just a rumor. Also I wanted to ask if there is any new information.
Does anyone have new information?
Our team leader told us that it'll be held in Sarajevo and that they are currently looking at early to mid August for the date. Of course, as with any Jboi nothing is for sure yet and should be taken with a grain of salt.
Can anyone post their country's team? Serbian team is: - SRB1 Marko Sisovic - SRB2 Momcilo Tosic - SRB3 David Milinkovic - SRB4 Mladen Puzic (aka me)
I don't think anybody except me has a cf account(and I just recently joined), but I'll ask them and add it if they have one.
Well that's nice. I actually didn't think there will be a JBOI. So current Bulgaria team is:
The ressults aren't final though. The fift guy is close to the forth and the final results will be known on 13th of June. In fact I think the one who won't go will be me, because I participate in the big group (I tried going to IOI but failed :D). But so far the team is almost sure. There is a possibility that Stanislav Nikolov (the fifth guy) will change with one of the first 4.
I would also love to hear other teams :)
PS: I think Momcilo had a CF account
What do you mean by the big group, like high school competition? I got to the National Olympiad, but failed miserably. What grade are you in? If we don't meet in Sarajevo, at least we'll meet in Shumen :D
I don't have a way to ask Momcilo at the moment, but I'll see him in a month so I'll update it then.
PS: Sorry, down voted you comment on accident and it won't let me reverse it.
Yes, Tosic, looking forward to seeing you (in case you do go) and congrats for being the first :)
And also looking forward to seeing all of the teams and the Serb team in a month!
Someone knows whether Polish guys are participating? It's going to be fun then :)
The final romanian team is:
Final Bulgaria team:
1) Radoslav Dimitrov — radoslav11
2) Ivo Karagyozov — JustInCase
3) Dobrin Bashev
4) Stanislav Nikolov
Sorry to inform you guys that JBOI actually won't be held in Sarajevo this year. Just got the news that the organizers gave up on doing it, and they are currently waiting for someone to sign up to be the organizer. If somebody does, it will be around the same date as last year,if not I guess it'll be Shumen.
Can someone give the email of organizers, that I could ask information, to register, the thing is that, our country will participate for the first time, so I need email to ask some info from organizers
That's the thing. It still hasn't been the decided who the organizers are, it will be known only once a country signs up to be the organizer.
Any news anyone?
Any new information?
Our teacher told us there won't be a JBOI this year. Do you have the same information? It's so fucked up :(
I haven't heard anything from our team leader recently, but currently that seems the case. Although last year we only learned about JBOI in August I believe, so there is still hope. Maybe Cyprus or someone else will sign up? Hope so. If no one does, it won't be the first time it happened, also happened in 2009,2010 and 2013, when Shumen was official JBOI.
Sorry for my last message. I was wrong! 15 minutes ago our techer called me to say tha JBOI will be held in September again in Macedonia. So it's good that there will be a JBOI!
Do you have the exact dates of the competition because our teachers told us that it would be between 5 and 25 of September but they didn't know when exactly.
Thanks for good news..>)
Guys! Do anyone know the exact date of JBOI?
any news?
A few seconds ago our teacher send us an e-mail which says that JBOI will be held in Skopje, Macedonia. The competition will take place from 17th to 22nd of September.
Poland will participate, too! Yay! :)
can you link their CF profiles :)
None of those guys is active on codeforces.
Good thing to hear! Who is participating from Poland? :)
Most likely Mateusz, Marek (same as last year) + Adrian and Mieszko. You'll meet them :D
They will be unofficial like last year, correct? Looking forward to meeting them :D
Me too! And reuniting with the others :)
I hope so. It might not be the only one Polish surprise — maybe you will have an opportunity to solve my problem. I've tried to contribute, send message to the Chairman — got no answer though :P
Can someone tell us teams other than Serbia, Bulgaria and Romania?
The official site of JBOI 2016 is jboi2016.cs.org.mk
So tomorrow this thing finally starts. Not sure if anyone still checks this thread, but good luck to everyone and looking forward to meeting you all tomorrow! :)
Something is wrong with the ranking :(
UPD: Now it works, good job, I_Love_Tina! :)
Ranking is up! Any way to see the problems?
Maybe I_Love_Tina can leave now and tell us :D
Hey guys, today was the first day of the competition. The problem statements can be found here:
Problem 1: Swaps
Problem 2: Donations
Problem 3: Party of Programmers
They will probably be uploaded in mendo sometime soon.
Something is wrong with the ranking... again...
It's up now! I guess the problems are harder than day 1.
Is there any possible way to view the problems before the end of the competition?
Here Jboi 2016 Champion I_Love_Tina!
Congratulations :)
Reality was unreal, congratulations :D Also congrats, radoslav11 :)
Here are the final ranks.
UPD: I was trying to upload it from my phone but I didn't succeed.
That's not how you link to images. You have to link to the image file itself, not a page containing the image beside a lot of other things.
Well, congratz I_Love_Tina for being the first! :)
Kind of sweet revenge that radoslav11 was last year one place higher than me and now my problem took him out of #1 spot. Anyway, what are your opinions on the quality of the problemset?
How can we access day2 problems?
As far as I understood from talking with some of the organizers: the tasks will (most likely) be published on the website (or MENDO) either this weekend or early next week. I know today everyone that was an organizer will be driving teams to the airport, train station, etc (as it's the departure day), so I don't believe much work will get done. But all the team leaders probably have the tasks on their computers, so maybe some of them will publish them earlier.
Btw, Miyukine, as far as I see, even if radoslav11 matched reality's score on your task, they wouldn't have changed places (if I got what task is yours correctly, as they referred to it as "the polish task" or something :)). Btw, they both got gold, so it doesn't even matter I guess.
I like the fact that there were tasks suggested (given) from multiple countries for this JBOI (being the 10th, so a milestone). I believe besides Poland, there was a task from Bulgaria, from a guy who lives in Canada, maybe others (not sure). So that's nice. The results make it seem like the tasks were a bit too difficult for most contestants though — or at least, that there wasn't at least one "easy task".
Well at least I got a gold medal :D
The second day for me was a total failure. I didn't plan my time correctly. I shouldn't have spent debugging the first problem for 3 hours. Also I should have read the 3rd problem on the contest, not after it. It was (in my opinion) the best but it was rather easy to get it for full score. Second problem was a pretty easy idea but you needed to implement it very well -which isn't really simple to do (I got just 55 points because of bad implementation). First was pretty simple. You just had 3 cases. I spent 3 hours debugging a correct solution and in the end the mistake turned out to be that I divided the whole result by 4, not just the result for one of the cases and couldn't finish writing it in time. So I think this is the reason I failed. If I had started with the 3rd problem I think I should have gotten at least 155 points but at least for next time I will know to not spent my whole time on one problem. And also I will know to read all the problems at the beginning of the competition :D
Now about the difficulty of the problems. IMO first day's problems were pretty simple but there really wasn't a "easy task". First one was a DP with partial minimum but if one hasn't seen a problem like that it would have been pretty hard for him to come with the solution. Second was pretty nice but in my opinion it was given in a bad way — I mean the blocked range. The blocked range was [0; n/8) U (n — n/8; n — 1]. We can see that if we have a count which gives n as an answer it always won't be in the blocked range. So you could simply do a binary search with count("name!=bidik || money >= x") == n, where x is the value from the binary search. I_Love_Tina did this solution. I didn't see that constraint and did another solution which worked for [0; n/8) U (n — n/8; n]. 3rd problem was also nice (maybe the best from day 1). I think I got the idea pretty fast but again I was stuck debugging a really simple corner test for a long time. So in this day there wasn't a single "easy task" but if I have to say which was the easiest problem, I would go with the first one.
So after I talked a bit about the problems I have one question to the organisers. Why was the competition just 3 hours and 45 minutes???? As I remember it has been 5 hours long. If you change the time of the competition at least mention it on the website.
Apart from the competition the organization this year was much better than last year.
In the end I want to thank all participants, team leaders, organisers and local guides for making such a great event!
I made the same mistake as radoslav11 at IOI,i think i learned my lesson.
For me the problems for the first day were very easy.The first problem is a simple dp,the second has a very simple solution and the third is a simple dfs / bfs problem.I think that by difficulty they are div 2 B / C.
The second day was different.The first task had a lot of cases.Fortunately i wrote the solution from the first with a single bug in a case which i found in ~ 30 minutes.
The second problem i didn't like because of too many dimensions,there were too many restriction and because of that i can't concentrate,so after finding that i am the first while returning from restroom i didn't even begin to code it.
The third problem was not very hard,the condition for B was obvious while for A was easy to observe from sample but i hadn't a complete proof,firstly i wrote both condition but i had a bug and i erased all the code and added only condition for B,after submitting for 50 points and finding that i'm the first and the difference is not so small,i just forgot about that problem.
Comparing with last year there was feedback,thanks you very much for it.I think Jboi should be an IOI for smaller participants,so adding subtasks and full feedback made it very close to IOI conditions.
Also i think adding subtask was a great idea because it kills random written solutions which have the same complexity but more points.
As radoslav11 said,thanks everyone for organising the event.
Dislike!!!!
Too!!!!
So here is the opinion of someone that didn't get a gold medal. In fact I didn't get a medal at all. First of all, the organization of activities out of competition was great. The local guides were nice, and a lot of activities were fun. Macedonia is very beautiful.
Second of all, I'll try not to bash the problems too much. It's incredibly hard to make a good problemset for JBOI. There are guys like radoslav11 and I_Love_Tina that are lightyears in front of other contestants. The organizers obviously didn't want perfect scores as that makes the distribution of medals pretty hard. That's why they made Day 2 so hard. But I think that in their quest to keep Radoslav and Gabriel from perfect scores they forgot about the little guys. In the end 38/600 points was enough for a bronze. In my opinion that ruins the point of the competition. The competition should be who can solve the most problems, sure it doesn't have to be a 100 on all problems, but it's supposed to be at least majority. It shouldn't be who can get the most points without solving problems. (of course that doesn't include guys like Radoslav, Gabriel, the Romanians and everyone else that actually managed to solve full tasks). What makes it worse is that I believe we were promised at least one 'easy' task on each day.
Now, I have to bash the problems a bit. Specifically P2 from Day1 and P1 from Day2. I'll start with the latter. If I_Love_Tina's solution really is the intended one, then I find this problem very ugly. It was just a way to keep people from having 600 (along with P2 from Day2). There shouldn't be that many disjoint cases in a problem that doesn't really have another idea. Anyways, congrats to everyone that solved it! Now concerning P2 from Day1. This problem was an interactive task for those that haven't read it. Yet, we didn't even get a mini grader, like it's a tradition on IOI and similar contests. Now, I know experienced contestants might disagree with me, but I dislike having to use the testing section of CMS (which wasn't even explained for those who never used CMS before), I like debugging code on my PC, not on a website. Anyways, the call for the function was very confusing. I kept getting errors like (paraphrasing) "Invalid syntax in the parameter of function count()" and stuff like that, even though I closely followed the syntax stated in the problem. I even asked if some syntax is valid, they said yes, and when I simply copy pasted it into my code I kept getting an error. Later they told me (if I understood well enough) that the problem was that I called the function more times than the function expected (still in the limit of the problem). The problem wasn't that hard, but the freaking syntax held me from having not 0 on that problem. I think that's not okay. I believe that this is one of the big factors for me having 0 on Day2, since I was completely depressed that I only had 14 on Day1 (even though I could solved P2 for at least 20 points, possibly a lot more).
Sorry for the super long comment.
And of course, again, congratulations to radoslav11 and I_Love_Tina!
I agree that the competition should be who can solve the most problems but i found the tasks easier than last year for the first day,i think the organisers aren't guilty,the problem is that participants are really weaker than usually,they can't predict such things.There was an option to give less medals to make harder to obtain medal but still everybody wants medals so they decided to give medals until 38 points.
I also think that it is very bad when two participants with difference more than 200 points have the same medal,the medal begins to devalue.
Funny fact:I could get bronze medal only by writing brute on third task,my brute had more that 38 points.
UPD.It reminds me about Romanian Masters of Informatics 2014 but that's it,now nothing can be done,both competitions lost their value of bronze and silver(IMO).
Well you also have to realize that this is actually some people's first times seeing subtasks. You and many of the top guys and girls know them because you're IOI-trained, but I can assure you that a lot of countries don't have subtasks on junior programming competitions. It can be hard to adjust to them, luckily I participated in some senior competitions last year. Now again, I don't think think the organizers are guilty. They were put in a tough spot and I don't think the IOI medal rules can realistically apply to JBOI where there are 10x less participants and the level of knowledge of participants is really low, but I do think subtasks are necessary if they want to make JBOI a more valuable competition. I think they should've made day2 problems a bit more doable when they saw terrible results for day1, for instance leave p2 to prevent perfect scores and make the other two easier so the participants on the lower part of the ranglist can realistically compare.
Other than that, I think the organizers did a great job and I hope that JBOI only becomes better every year, even if this is the last year I can participate.
What is the point behind that, what's hard in adjusting to them? It's just that you can't easily steal points with things like if(N==1) {do something} or writing some wrong greedy solutions. Which is good in my opinion since you don't go to JBOI to hack tests, right?
Also, what is the problem in applying the IOI medal rules, there are 10 times less participants and 10 times less medals, this rule is really really common (if you speak about the 1:2:3:6 rule).
Well, that was participants' problem, not jury's. I haven't read the problems yet, because I want to do it when I have enough time to think about them but assuming that they saw those terrible scores and they really should care about that (which is not true), then... eh, they also saw perfect scores which they didn't want to see so they may have wanted to make the second day harder. And here you suggested to leave only p2 but here is the downside of it (from their perspective, still if your logic that they should care is true) — I think Gabi and Rado could easily handle one hard problem. You saw the reason for Rado's points — he didn't plan his time correctly. And with just one hard problem you don't have much to plan — solve the two easy problems fast and go to the hard one, moreover he is quite experienced and this won't be a problem for him. I guess he just wanted 300 and couldn't accept the fact that he didn't solve the second one when he started it (last year I did that on our NOI, fortunately I didn't fail too much :D).
And one last thing, regarding your previous comment. You said one of the tasks was interactive and they didn't provide a sample grader. Well, that's bad, I think. You could write one yourself but still if you see that for the first time you don't really know what it should look like so yeah, it was a bad decision not to provide a grader :)
I never said that JBOI shouldn't have subtasks, or that subtasks are stupid. I just said that it should be considered when looking at the results. Until now there weren't subtasks and that's why (IMO) the results were better for a lot of people, and not only that the participants were that much stronger (which still could be the case). Anyways, I do think having subtasks was a good idea.
Well this might be an odd case, but in situations like this (where first and last silver have close to 200 point difference) it really devalues the medal. And when there are much less contestants and they are much worse than guys at IOI (with of course some exceptions) the rule provides too many people with medals, where some guys that were gray on CF until recently got a medal.
Now that you say that, I do see that just leaving P2 was a bad idea. But I still think the jury should care that the lower part of the ranglist gets a realistic comparation. Competition that did this well was 2014, where it really was who can solve the most problems, not who can get the most points without solving problems. Sure they had one perfect score, but the golds seem pretty realistically divided. Anyways, I think that the scores under 100 were pretty unrealistic, but again, no competition is perfect.
Okay, last year there were some "stolen points" that wouldn't be there if there were subtasks but we also had no feedback that year (not even a single test, however, I understood that Macedonia had to do many things in a really short period of time so it couldn't be a perfect contest). I had a correct solution to a problem in both days that had just partial score or zero. That was not because I was trying to hack tests, it was just because of the lack of feedback. Someone can say that it's my fault that I didn't write my codes without mistake — ok, you are partially right, I didn't feel comfortable doing stress testing under Windows :D. I won't go into details, the discussion can be found in the earlier comments. Points stolen because of intentionally written wrong solutions were minor, I only heard of 5 points stolen by petrescu on the second day, maybe there were few other cases I am not aware of.
True! But it is a tradition for most of the olympiads to do that, yeah, in such cases it's far from perfect.
And about the participants in the lower part of the results getting a realistic comparison... Yeah, it would be good to have one or two easier problems but "easy" has different meanings for different people, you see I_Love_Tina said the three from the first day were simpler than those last year and it took him just an hour and 20 minutes to solve them all. So it is not that simple for the organizers to guess how easy a task should be, and of course it's a balkan olympiad — even the easiest problem shouldn't be that easy.
Regarding JBOI 2014, yeah a kind of well-balanced medals. But that year there wasn't a hard problem (or maybe just one — Strategy because some people couldn't see why the solution is fast enough but the idea isn't that hard) which allowed many participants to get a lot of points. But you can see that exactly the opposite bad thing happened there — the differences between different medals were too small — 20 points for Gold/Silver and 30 points for Silver/Bronze, that's not cool, especially if you are ha1vanka...
To sum up, it is very hard (not to say impossible) to predict how well-balanced the ranking will be based on the problems. Providing a well-balanced problemset isn't an easy thing, too (however, I have seen it twice — my favourite JBOI problemsets are 2011 and 2012) so in my opinion we shouldn't judge the organizers for giving too hard problems. I know how hard it is to lose something you really wanted to achieve in the first day of a 2-day competition (for me it was the gold from JBOI last year, the IOI team on the first day of our NOI this year) so I understand how you feel :) Just forget it (don't forget the moments you had and the people you met there though) and good luck in future! :)
For those who want to try the problems, the official problem statements are now uploaded in mendo.