Qingyu's blog

IOI 2025 China Team Selection — Current Standings
By Qingyu, 6 weeks ago, In English

Hi, everyone.

The first stage of the IOI 2025 China Team Selection began yesterday. The top 50 participants from the 2024 National Olympiad in Informatics (NOI) will compete for a spot on the Chinese national team for IOI 2025.

The rule of selecting CHN team this year:

  • Homework (10%): also known as mutual tests, where the students were asked to prepare a task (5%), and participate in the contests made by other students (5%)
  • First stage (CTT; 54%; Dec 3, 2024 — Dec 5, 2024): three contests in classic olympiad format, where each contest worthes 18% of the score. Top 30 participants will advance to the final stage.
  • Final stage (CTS; 36%; Jan 20, 2025 — Jan 22, 2025): two contests in classic olympiad format, where each contest worthes 18% of the score.

The current scoreboard can be found here.

Past problems of the China IOI Team Selections can be found here (first stage and final stage). I will upload all the tasks once they can be publicly shared.

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6 weeks ago, # |
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is there any scoreboard that can be accessed in china?

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6 weeks ago, # |
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I'm wondering if you can connect the participants with their cf handles.

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6 weeks ago, # |
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I'm curious, but how is the homework scored (specifically on the part of setting problem)?

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    6 weeks ago, # ^ |
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    Submit any task = 3.2p

    Task is used in mutual tests(I think any competitive programming problem will be used) = 0.6p

    Feedback from participants and coaches(the weirdest part, easy problems are getting better score) = 1.2p

    Participate in mutual tests with >=60p = 0.6p*7=4.2p

    Participate in mutual tests with rank <=20 = 0.16p*5=0.8p

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6 weeks ago, # |
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is the allegation true that being a top 50 candidate in the NOI is harder than winning gold at the IOI?

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    4 weeks ago, # ^ |
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    I don't know.But as a student from China,I can tell you one thing:China's top 50 players are just as good as international grandmaster.

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    4 weeks ago, # ^ |
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    Some of them are better than international grandmaster.For example,one student from my school called grass8sheep.He ranked 18th in this year's NOI.He is a red coder too,but in my opinion he will be a black-red coder in the future.

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6 weeks ago, # |
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They choose their IOI team really early. We only have our team after APIO, which is often in late May. China is just better.

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4 weeks ago, # |
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The tasks have been published. You may upsolve the problems and view the specific scoreboard for each contest here.

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4 weeks ago, # |
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Wondering where can one find the solution to previous CTT/CST problems?

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4 weeks ago, # |
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How does it happen that people in the top 10 of CNOI tend to perform worse than people from top 20? If you got the first place at CNOI, it can't be just luck – but still the winner is now second to last.

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    4 weeks ago, # ^ |
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    It's just luck.

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    4 weeks ago, # ^ |
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    maybe this time the luck is not on his side, or maybe he has tried his best on his own this time, who knows?

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    4 weeks ago, # ^ |
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    I think this happens because the specific way problems are created and arranged for NOI and CTT is quite different. I don’t have solid proof, but here are a few key differences I’ve noticed:

    • Problem Order: In NOI, problems are always arranged in increasing difficulty, making it easier to pace yourself during the contest. On the other hand, CTT shuffles them randomly, which makes strategizing much harder.
    • Partial Scores:
    • NOI’s partial scoring system is pretty well thought out. It encourages you to move toward the full solution while still giving significant points for partial progress. You can often score quite a bit even if you don’t solve a problem completely.
    • CTT, however, seems to reward full solutions more and doesn’t benefit partial approaches as much. Some partial scoring setups even feel intentionally frustrating—like CTT24 D2T2, for example.
    • Interactive Problems: NOI typically has zero to one interactive problem, while CTT throws in several. This time, there were three interactive problems in total.

    Another thing to consider is that after NOI, a lot of Chinese participants start pre-university programs at THU or PKU, where they spend a lot of time on college-level courses. That takes away from their training time.

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4 weeks ago, # |
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I see some students are taking part unofficially, like Kevin or 郑煦翔. How can a student be an unofficial participant?

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    4 weeks ago, # ^ |
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    They are still in Junior High.

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      4 weeks ago, # ^ |
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      Hmm, so anyone can be an unofficial participant? I thought they must meet some requirements.

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