Hi codeforces!

Last year I got the chance to visit IOI 2025 in Bolivia (together with Kuroba), my first time back at an IOI after 7 years. It was a really fun experience reconnecting with the IOI community, watching the contest, and solving the problems together with all the teams.

This year, the firm I work with, Hudson River Trading, is sponsoring both EGOI and IOI, and some of us will be onsite at EGOI next week and at IOI later this summer. To get warmed up, we were honoured to work with Eljakim Schrijvers from IOI, to make a series of walkthrough videos for some of the IOI 2025 problems, which we'll be releasing over the next few weeks :)

The first video is for Souvenirs, featuring my colleague Katherine Li, who will be at EGOI!

>>> link <<<

Coming soon, is World Map (featuring Kuroba) and Festival (with myself)- stay tuned!

We tried to make these feel less like "here is the official editorial" and more like understanding the actual thought process behind how you arrive at the solution. Hopefully they're useful, whether you're actively training or just watching IOI problems for fun.

More videos coming soon -- good luck to everyone competing at EGOI and IOI this year!

Hi everyone,

I am currently participating in the gym contest CCPC 2016-2017, Finals (http://codeforces.me/gym/101206). It appears that there may be a problem with test data for problem L, but I don't know how to fix it.

My team felt that something may have gone wrong when we noticed that most ghost participants had solved the problem, but none of the live competitors managed to solve it. My team's code failed on test 1, which is usually sample data, but it passes on local tests and on custom invocation.

After enabling coach mode in gym, I found that there was a mistake in test 1 of problem L, and it looks like the sample test case was miscopied. Unfortunately I don't know how to fix this issue, and I could only notify competing teams that there was an issue.

If you have the time and know how to work with Polygon, can you please change the test case to match the problem data?

Thanks.

-jerry

PS: I'm not sure if I was supposed to enable coach mode in this situation, but I hope that it was the right decision.