TozanSoutherpacks's blog

By TozanSoutherpacks, history, 23 months ago, In English,

I think this is the right time of showing the way of team selection in Japan, so I spare time for writing a blog, instead of preparing for Distributed Code Jam finals.

Compared to other countries, Japanese selection rules are very simple. Perhaps this is the simplest rule among the countries getting gold medal almost every year.

There are 3 rounds to go to IOI. Each round is independent so even if you don't do well in the previous round, you wouldn't have disadvantages for the next round (as long as you are qualified).

1. JOI Qualification Round (JOI 予選)

The number of participants is a bit larger than 1,000. There are 6 tasks and contest duration is 3 hours. Judging from the past years' problems, the first task is really easy (like "I have 10 integers, and I'll give you 9 of my integers and the sum of all my integers. Can you guess the remaining integer?"), and about 5 students can solve the last task. This round is held online, and it seems AtCoder system will be used for the first time this year. If you have participated in Selection Camp before, you are automatically qualified to the Final Round. Otherwise, about 60 students with highest score advance to the next round, and there are other qualified students that even I don't know how are selected ( BLACK BOX :( ).

You can find and solve past problems on Aizu Online Judge. Some problems are translated in English and some can be read through Google Translate.

2. JOI Final Round (JOI 本選)

This is the national championship. The top 3 members are awarded medals and laptops. The number of participants is 70 to 80, and the contest is held in Tokyo or Tsukuba (the next IOI's place). You don't have to pay for your travel fee and staying cost, and the contest takes 2 days (including practice session and party). That's why I started to participate in JOI when I was 8th grade.

Usually, the contest has 5 problems and 4 hours, and cutoff line is between 2 full-solutions and 3 full-solutions (I think). Sometimes the last problem of this round is the hardest problem of the year.

You can also find and solve past problems on Aizu Online Judge.

3. JOI Spring Camp (JOI 春合宿)

The most important round for participants. The national team is selected by the result of this camp. Around 20 students with highest score in the Final Round can participate in this camp.

Usually, the camp contains 4 competition days (the camp itself is 7 days long, including practice round, lectures, and awarding ceremony of the Final Round). In each day, there's an IOI-styled contest with 3 or 4 problems and 5 hours. Despite only batch-style problems are used in previous two rounds, various kinds of problems are seen in this camp, including output-only, communication task, encode-decode task, etc.

The problems used in the camp are known as "toughest yet most interesting problems" in Japan. I agree with the "toughest" for this year, because even yutaka1999 couldn't solve more than a half of the problems. "Most interesting"? I can't judge it since there are so many interesting contests in Japan, thanks to AtCoder.

The top 4 students are selected for Japanese national team of IOI. Oh, what a simple selecting method.

You can find past problems here (Japanese) and judge is on AtCoder (example, by changing the URL you can submit to past problems). Luckily, this year's problems are translated in English, so you can practice without the help of Google Translate (awoo).

4. JOI Open Contest

Practice contest for IOI, usually held in June or July. Usually 3 problems in 5 hours.

This is not related to national team selection, so students can be relaxed to take part in the contest. the problem statement is provided in both Japanese and English. You can find further explanation on Codeforces (maybe joisino posts about this contest every year).

5. Conclusion

Practicing with other country's OI problems seems very helpful, but they are often written only in their mother languages. Translating problems is a demanding work and nobody wants to do without payment. That means learning a new language for competitive programming practice makes sense (really?).

 
 
 
 
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23 months ago, # |
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Who are the problem setters for these contests?

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23 months ago, # |
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Actually, JOI Spring Camp is very difficult. This year 14 people (including me) participated in spring camp and I got 6th place (2nd runner-up), but I wasn't able to solve any problem. (Only partial points, 303/1200 pts) JOI Spring camp problems are very tough but helpful.

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    23 months ago, # ^ |
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    So you should solve these problems asap maybe? Why not?

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    23 months ago, # ^ |
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    isn't 2nd runner-up third place instead?

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23 months ago, # |
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Great write up! Would be great if other countries can share how their selection process works so we can learn from each other!

Though seems like there's not much training in the selection process? So most participant get their own training?

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23 months ago, # |
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thanks for writing this, now I can practice japanese and competitive programming at the same time (^。^)

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23 months ago, # |
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So...I could have entered the Japanese team this year(I only did 3 days on JOI spring camp this year and outscored all other participants already), and the Japanese team would have one more silver medal next year lol

I was obviously kidding. I am not a Japanese citizen so I definitely can't enter the Japanese team. My connection to Codeforces is kind of weak so I often accidentally click "save" multiple times because the browser isn't responding, resulting in so many duplicate revisions.

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    23 months ago, # ^ |
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    Maybe most of JOI organizers would welcome you — since all contestants will be first time to IOI next year. There's possibility that silver medal is best among them; of course I hope they get a gold, though.

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      23 months ago, # ^ |
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      There's possibility that silver medal is best among them; of course I hope they get a gold, though.

      That's such a big possibility because:

      • Japan team got rank 1, 4 and 5 at IOI this year.
      • Japan teams have been winning at least one gold medal in every IOI since 2006 (they didn't participate prior to that time if I'm correct)
      • Japan will be the host next year.

      end of sarcasm =)

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        23 months ago, # ^ |
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        Just an information, but my next year's IOI member prediction is:

        1. ?????: 10th grader, About 350pts (5th rank, but I don't know the exact score. Though I'm certain that his score is 304~399) in JOI spring camp, Atcoder rating is around 2600 is the highest rating among next JOI participants, and also currently only one coder that is Master or above in Codeforces, among next JOI participants.
        2. E869120: 9th grader, 303pts (6th rank) in JOI spring camp, Atcoder rating 2582
        3. WA_TLE: 11th grader, 236pts in JOI spring camp online mirror (the score is between 7th and 8th rank in JOI spring camp), Atcoder rating 2280
        4. naoki2016: 8th grader, He is not participated in JOI spring camp, and his Atcoder rating is 2086 but his improving speed is very high (looking at rating graph in Atcoder)

        There is still no red coder, so I think possibility is not very high (but still ~50% possible)

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          23 months ago, # ^ |
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          Why no square1001? I think you are in the candidate obviously, because your CF rating is higher than me, and your TopCoder rating is highest of people who is eligible for next IOI. In addition, you got 7th place, ~250 pts in JOI spring camp 2017. I think there is no reason that you are not in the candidate. Why did you predict such a prediction?

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          23 months ago, # ^ |
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          Codeforces rating means nothing in terms of IOI results. In fact, it could have contrary effects :)

          Let's see the results of 5 participants with the highest maximal rating on codeforces.

          Among me, yutaka1999, jiaqiyang, geniucos, reyna, one was the champion, three got silver, and the other got bronze.

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          11 months ago, # ^ |
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          Do you still think that Japan will not do well in IOI this year?

          You have to think again :)

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23 months ago, # |
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Was wasn't Japan participating in IOI before 2006? You didn't know about it?

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    23 months ago, # ^ |
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    Depending on JOI website, there were economic or financial problems.

    In fact, JOI committee sent the people to IOI from 1994-1997. But since economic and financial problems, once JOI quit managing and sending people to IOI. In 2005, a sponser came and those problem solved. This is why JOI restart at 2006.

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23 months ago, # |
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Am I the only one willing to pay for a centralized well done translation of these tasks? Maybe if we can gather more than one, we could provide a decent sum of money for some volunteers in exchange for their translation. Anybody with me?

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23 months ago, # |
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Other qualified students that even I don't know how are selected ( BLACK BOX :( ).

So I'll write it. The member of JOI Final Round qualifier is (according to JOI website (JAPANESE)):

  1. People who got A-rank (atmost 80 people) in JOI Qual Round
  2. People who advanced spring camp last year
  3. Winner in some programming contest last year (PC Koshien, Supercomputing Contest, Kosen Programming Contest)
  4. Top 2 student in each "block" (Block is like a "province" in China, or "states" in USA or Canada. There are six blocks in Japan)
  5. Top 2 girl student
  6. Some school that JOI decided (it says 指定校) 's student can advance to Final Round (If the participants in schools is 5-29, at least 1 people can advance to Final Round, 30-59 is 2 people, ≥60 is 3 people)

Usually 1. and 2. or 3. collides, so I think 2. and 3. has less meaning but able to relieve :) But all of 3. contest is only eligible for high school student :( And I think 6. is super-mystery.

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23 months ago, # |
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Perhaps this is the simplest rule among the countries getting gold medal almost every year. — I beg to differ

Our process ends at POI final round and TOP4 is chosen to IOI. And we don't have any shitty rules like ones square1001 mentioned. We have a summer camp, but it is meant to be fun, same on PMO. Both on POI and PMO contestants expressed ideas to select people based on camp's results, but we don't want people to be stressed during them, necessarily go to beds before midnight to perform well or be in a troublesome situation if they can't attend camp or need to miss one day etc. It has its advantages which I described, but also increases variance of results and sometime some good contestants miss their chance of going to IOI/IMO and less skilled participants take their spots.

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    23 months ago, # ^ |
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    You beat me ;)

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    23 months ago, # ^ |
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    I'll offer our own account (from Vietnam).

    There are two national qualification rounds, currently restricted to only high school students (so each has at most 3 chances). As mentioned below, each region has their own selection test to choose students for the national round.

    1. Vietnam Olympiad in Informatics (VOI). Around 400 students participate, top 32 move to the second round. This consists of two days of competition, each day lasts 3 hours. The students participate from the region they qualify.

    2. Team Selection Test (TST). This consists of two days, each lasts five hours and uses the same CMS system as in IOI, although most problems are traditionally algorithmic. EDITED: Top 15 qualifies for Asia-Pacific Informatic Olympiad (APIO), where the combined score from TST and APIO (by considering APIO as a single contest day) are used to select the top 4. This is centrally organized in Hanoi, with all expenses paid by organizers.

    When the team is formed, the training camp typically starts from May till about 1 week before IOI. All expenses are paid by the Ministry of Education.

    Currently test data and reasonably good editorials are not available, but AFAIK the problems in the first round (in Vietnamese) are posted on vn.spoj.com with unofficial test data (its difficulty is somewhat easier than a typical CF around, I would say the hardest problem is around Div 1 C/D). For the second round, probably we need to reorganize and put into an official document some time soon..

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      23 months ago, # ^ |
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      It's top 15 who qualifies for APIO since 2014.

      Sadly, it wasn't enough to save me from a tragic TST day 2 lmao

      Also there are provincial selection contests but they aren't nationwide (different problem sets for different provinces) so yeah technically we have 2 rounds.

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        23 months ago, # ^ |
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        Too bad we missed out MofK's silver medal this year :(. Hope you get that medal in Beijing.

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        23 months ago, # ^ |
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        The mistake was the fuckin Trimino problem.

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23 months ago, # |
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The country get gold medals almost every year


Yes. In fact, Japan almost always get gold medal. In addition, next year IOI2018, the hosting country is Japan so it is important though all of IOI participants from Japan are first time of IOI. And, this year Japanese competitors got 1, 4, 5-th place (Congratulations!)

So I have to do my best to practicing/doing for competitive programming and IOI, and I will do.

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    23 months ago, # ^ |
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    Why downvotes?

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      23 months ago, # ^ |
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      because of So I have to do my best to practicing/doing for competitive programming and IOI, and I will do.

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5 months ago, # |
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Can anyone estimate what's the difficulty of USACO platinum contests in relation to say, Japanese Final Round/Spring training camp contests?