cszyf's blog

Look for cp information
By cszyf, history, 16 hours ago, In English

i'm recently doing a research on southeastern asian countries' imformatic olympics situation, but have long been struggling with the lack of data. i would really appreciate it if you could provide me with these countries' ioi team selection system and problems, also the codeforces id of ioi team members, so that i can properly evaluate the development of cp in the region. targeted countries: malaysia, singapore, thailand, vietnam, indonesia

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15 hours ago, # |
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Here a some links with CF handles of attendees for past few IOIs

2024

2023 and 2023

2022

2021

2020

You can find more info at stats.ioinformatics.org/contestants/(insert year here)

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    5 hours ago, # ^ |
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    thx alot, i've been looking for these blogs for a while but didn't succeed in finding them.

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7 hours ago, # |
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From Thailand.

Here's the selection rounds from start to finish. A similar system is used for the other subjects too.

  • POSN 1

  • POSN 2

  • TOI

  • Oct camp

  • March camp

  • May camp

  • IOI

For POSN 1 and 2, it's a regional selection by what we'd call "centers". There are around $$$10$$$ to $$$20$$$ centers in Thailand. Contestants are selected to POSN 1 by a paper test on math and logic (which I heard will change to analyzing Python code). Number of contestants, usually ranging from $$$20$$$ to $$$50$$$ in each center in POSN 1 and 2. The method of selection, training quality, and task quality depends on the center itself.

After that, five to six contestants from each center is selected to the TOI. You can find a pretty recent TOI exam (translated to English) in Codeforces Gym. The TOI is competed in two days, each day having three tasks and given five hours. The exam system is the same as IOI.

Around $$$20$$$ to $$$30$$$ top contestants are selected to Oct camp. $$$20$$$ will remain in March camp, around $$$10$$$ in May camp, and then selected for IOI. The exam system is the same, but the tasks are much harder compared to TOI. Soon, they'll change Oct-May camps into only two camps.

Next is on the tasks themselves, note that some remarks are mine and shouldn't be taken objectively.

Material covered in TOI is about that of USACO gold, maybe a bit less. The tasks are pretty standard, and I think you can get high score and go to Oct camp if you are good at well-known problems. In particular, DP is prevalent, accounting to about half of the tasks. Specifically, range DP or variants have been found in three consecutive years. Graphs and binary search can be found often. Problems on greedy and math are rare (except some counting/math with DP). I think the full-solve difficulty of TOI tasks are around 1300-1800 (might be pretty off here).

In all three IOI training camps, you'll learn material, but I find much of it as "too much" and not really necessary for IOI. The exams at the end of these camps don't feel that different to me. There's the practical (coding) exam which accounts for most of the score, and the theory (paper) exam which is a smaller portion. (70-30 for Oct, 85-15 for March, idk May).

In the 3-week span of Oct camp, you'll already learn most material found in IOI. Oct -> March selection tasks, according to the task authors, is meant to "measure your ability to apply the tricks learnt", but there's some decent thinking process required. The March and May camp, on the other hand, is meant to choose IOI representative, and will require more thinking. I'm in March camp right now, so can't remark further than this yet. The tasks are difficult, but not close to IOI.

Please DM for further information.

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