There are 100 problems left. I’ll do my best to solve all of the ones that are solvable in theory. Why don’t we all aim for AC on every problem?

I often receive direct messages, many of which I ignore, though I do respond to some. Here, I’ve decided to write down answers to some frequently asked questions.

Going forward, I will likely continue to ignore most messages. If you really want a response, I think I can at least give some kind of reply if you support me with a positive amount via https://github.com/sponsors/maspypy.

I will probably not respond to most of the comments that this article will receive. However, if there’s something interesting, I may add it to the article.

Are there any tips for improvement?

Such overly common questions are best asked to tools like ChatGPT.

Are there any introductory articles I should read? Are there any books on competitive programming?

Please search the internet using keywords like "codeforces, tutorial", "competitive programming book".

What should I do to aim for IOI or ICPC?

Since I have absolutely no experience with these, I recommend asking someone else.

What problems should beginners try?

I recommend ABC (AtCoder Beginner Contest). I think the difficulty and required techniques tend to be more consistent compared to Codeforces. However, be careful as the later problems in a contest can sometimes be quite difficult.

On Codeforces, studying from div4, div3, or Educational Rounds would be a good approach.

How can you reach color X in Y months?

When I started Codeforces, I was already a red coder on AtCoder, so I probably had around Y-level skill from the beginning. However, at this point, I actually switched my main language from Python to C++, so it took some time to get used to it.

How do you solve so many problems?

When I started Codeforces, I was already a red coder on AtCoder, so many problems were simply easy for me. For example, you can see from the standings that top players can solve div3-level contests in about 20 to 60 minutes. In the very beginning, I started with such problems, so solving dozens of problems a day was easy.

Do you solve problems by yourself?

Basically, yes. I think I've referred to editorials for about 50 to 200 problems so far (just an estimate). As the number of easy problems decreases, I expect to rely more on editorials for the remaining ones (300+ problems are remaining).

I generally don't copy code from others, but there have been a few exceptions. Such as several problems in April Fool contests (which I don’t enjoy), or problems where the judge or problem statement seems to be broken.

Also, for special language contests including Kotlin Heroes, I often convert my code into another language using AI. Note that doing this during a contest is considered cheating.

Should I solve problems by contest or by difficulty?

I've rarely done "virtual contests" as a practice. My recommendation is just solve problems that match your difficulty level. But that's just my personal approach. There are also top players who primarily train through virtual contests.

How do you manage your libraries and create submission files?

The libraries I manage can be found at: https://maspypy.github.io/library/ I use online-judge-tools/verification-helper to expand the includes for submission. See https://github.com/online-judge-tools/verification-helper/blob/master/README.md

Can you be a writer or tester of our contest?

While I want to contribute to the competitive programming community, I'm already doing such work on AtCoder and have limited capacity. So at the very least, I don't intend to accept requests sent via Codeforces messages for free. (I did accept a request once, but the problem statements and test cases were of poor quality at the time of request, and it was a lot of work.)

Please solve this problem, Here's a problem statement

I generally won't respond to such requests, as they might contribute to cheating in an ongoing contest.

Please write an editorial for this contest/problem

Please contact the contest organizer.

Hello.

I am Japanese and have been publishing some articles within the Japanese-speaking community for some time now. This is my first attempt at translating one of my Japanese explanatory articles into English. (This is also the first CodeForces blog for me).

The theme is the computation of formal power series composition and compositional inverse.

• FPS Composition and Compositional Inverse
  • (PART 1) Compositional Inverse and Power Projection
  • (PART 2) Composition Algorithm via Transposition Principle

A method to improve the known computational complexity for this theme was introduced by noshi91 in March 2024.

• https://noshi91.hatenablog.com/entry/2024/03/16/224034
• https://arxiv.org/abs/2404.05177 (noshi91 and Elegia)

Several blogs about this topic have been written within the Codeforces community.

• On implementing O(nlog(n)^2) algorithm of FPS composition (hly1204)
• Why is no one talking about the new fast polynomial composition algorithm? (Kapt)

However, I couldn't find any blogs, in Japanese or English, that thoroughly explore the following topics:

• How to implement them with a better constant factor.
• How to derive and implement the Composition Algorithm using Transposition Principle.

Therefore, I decided to explain this topic myself.

I have studied English to some extent, but I'm not very proficient. I received assistance from ChatGPT for translating many parts of the article. However, there might still be some incorrect English expressions remaining. If you notice any issues, please feel free to provide feedback.

If you find the article interesting, you can also support me through GitHub sponsors.

Actually, there is another article that has been requested for English translation, but I've left them untouched for quite some time. Maybe it's time to take on that translation challenge as well.

Thank you for reading.