Hello everyone, I just want share my idea for a simple bruteforce system to check for a repeat problem. What I've thought of won't prevent repeat problems from being written, but perhaps prevent them from being used in contest.

I propose that when a problem and code for the intended solution is written, all previous problem test cases are tested on it to see if anything is fully accepted with code that is written for the new problem. If such a problem is found, it can be manually reviewed for if it's just a coincidence or a repeat problem. This obviously won't detect every repeat problem due to different input requirements/formats, but I think it could help at least a little.

An example that would be submitted for manual review:

1804A - Lame King and 1452A - Robot Program while the problems aren't exactly the same, the same code could work for both.

197574009 and 197074161.

The problem author and contest organisors could then decide wether they should replace the problem or if it's dissimilar enough to use the newly written problem.

The example problem I gave above is simply due to my limited experience and I'm sure people could find other harder problems that would be the same.

Whilst this is by far not a perfect solution, it could be a small step towards helping with repeat problems showing up in contest. Thanks for reading!

Side note: I know this is probably another useless blog and will never actually be used, but I thought I should share on the off chance it isn't a useless idea.

Hello everyone, I just wanted to share an idea about blogs on codeforces to help new users.

Every once in a while people will make a blog about starting codeforces, that'll inevitably be downvoted (They always are). I feel like this can cause people to think the Codeforces community is much more toxic than it actually is and might turn people off ever wanting to interact with the community. So I think there should be an explanation of what blogs usually are used for on Codeforces when someone tries to write their first blog. I feel like this would help new users from making that mistake and make them feel more welcome when/if they do decide to write a blog that's accepted by the codeforces community. Just my opinion.

Hello everyone, I was wondering if someone could help me figure this out. I can't figure out why one of my solutions works and the other doesn't. Thanks.

1717C - Madoka and Formal Statement

Working 170972214

Not working 170970152

Hello everyone, I just wanted to share a quick idea that'll probably never be implemented, but on the off chance it is, I'll share it.

I think there should be a new difficulty tag that is set by the author of the problem before the contest (their perceived difficulty of that problem).

There are a few reasons I think this is a good idea. Firstly, I think there are a lot of problems that are rated higher than they're supposed to because they were simply further in the list of problems than the rest. Resulting in equally hard problems being rated higher due to less people solving them since they spent time on the previous problems and just didn't have time in contest.

Secondly, I think often times authors of problems miscalculate how hard a problem is. I think This might be an example of that. (12736 Solved on B, 987 Solved on C) and I think it would be useful to see both difficulties.

Thirdly, I think it would just be interesting to see what the authors think about their problems.

Anyway, thanks for reading. Have a great rest of your day!

After a long 19 months, I've finally reached Specialist! This is still only the beginning! But I'd like to say joining the Codeforces community and doing competitive programming has been amazing. It has helped me both develop my thinking/problem solving and has also been a very humbling experience. Before I started CP I was much more arrogant, when I joined in the first few days I made a blog saying I was coming for the number 1 spot, I was extremely overconfident in my ability. I've also had the opportunity to meet some great, incredibly talented people because of CP. So hey, thank you, everyone who has somehow contributed to the community, be it making rounds, writing blogs or being Mike. Now then, onward to Expert!

Side note: If any problem setter needs a tester, feel free to message me. I've always wanted to be a round tester.

Hello, could someone please explain this problem 450B - Jzzhu and Sequences to me. I've read the editorial and some other peoples code, but I'm not sure I completely understand it. Thanks in advance!

Hello everyone, today is International Teachers Day. So I thought I'd use this as an opportunity to thank those members of the community that have helped me learn or improve in my competitive programming journey and encourage you to do the same in the comments. I want them all to know their efforts are appreciated by all of us.

So here's my personal thank list:

galen_colin for his great screencasts and awesome topic streams. He's really great at explaining topics and solutions and has been extremely helpful.

Errichto for his constant streams with great explanations and his topic tutorial videos. He is an incredible teacher and has also been very helpful.

pllk for his competitive programmers handbook. It is in my opinion the best book out there to get started and has been once of the most helpful resources for me.

Monogon for giving me general advice on how to practice and improve.

E869120 for his super helpful PDF on how to practice and what topics to learn.

tmwilliamlin168 because I only discovered competitive programming though his Youtube channel and might not have ever discovered codeforces and competitive programming otherwise.

And last but not least I'd like to thank all the people who've wrote great educational blogs or helped answer others questions on blog. It would be way to many to list here, but I want them to know that their efforts are also greatly appreciated.

All of you are awesome and I hope you keep doing what you're doing. You've helped thousands of people. Thank you!

There are also many others I haven't included in my personal list that provide educational content, so please if someone has helped you learn. Make sure they know you appreciate their efforts!

Additional thanks: MikeMirzayanov and the rest of the Codeforces team. None of this would exist without them and it goes without saying how much I appreciate what they've made and the effort they've put in. This platform remains completely free for everyone and is truly great, even with any flaws it may have.

Thank you all and thanks for reading!

Hello everyone, I've spent a lot of time trying to solve this problem 1574C - Slay the Dragon, I've even read the editorial and tried implementing it myself, but every time it's too slow no matter what I try. So could someone please explain why this solution is too slow. Thanks in advance! 129796109

Just a simple feature I want added. I want there to be the option to thank the person answering questions in contest after they answer one of mine. Just a simple thank you button. Every time I ask a question I want to thank the person who spent time to answer my question, but don't want to waste more of their time by asking another question just saying "Thank you for answering my question". Please add it if it's not too much work MikeMirzayanov or anyone else from the Codeforces team.

Thanks for reading!

So I've got a question about problems that need prime numbers. How are you meant to approach them? More specifically, how do you approach problems that require you to calculate prime numbers and do something with them? Do you implement/copy paste something like the sieve of Eratosthenes every time or is there a better method? Thanks in advance.

Download here Please follow the instructions. (You don't need to download the source code to your PC.)

Update: There are now two versions for black and white nutella colours. Install link

Update 2: I have make it work with the new codeforces test case feature please report any issues you may have and enjoy. I also fixed new messages being too bright.

Hello everyone, so recently I've discovered a dark mode for Codeforces made by sigma_g. I liked his idea of making a dark mode, but in my opinion it didn't look very good. So I decided to fork his project and make my own version. In my opinion it looks a lot better and I hope you'll like it. I tried to make it look like the CSES dark mode with a few changes. Also I'm always open to criticism and feedback, also if anyone wants to contribute to this project feel free to message me or just submit a pull request if you've already made something. You can download and install it HERE the installation instructions are also there and it's super simple. Enjoy!

I would also like to sincerely thank sigma_g, I would not have made this without his original version.

Right, so I'm not the best at making blogs but here's my attempt at proposing a coherent solution to cheating and cheating blogs.

1. Add a report section: If someone suspects someone else of cheating they can submit the solutions of the people suspected of cheating. I then propose two options of further action: One of the people on the Codeforces team looks at those solutions and gives a final verdict. I think that might not be possible because they're probably busy people who'd rather spend time developing features for the site or making general improvement or helping with new rounds etc. The second option would be have the community decide. Have cases looked at anonymously by people over a certain rating and problems solved (to avoid high rated people with smurf accounts being able to decide the verdict.), when a case if being reviewed multiple people give their verdict on if the people are cheating and take action only in VERY overwhelming cheating verdicts to maximally limit false positives. Also if someone sees code being shared during the contest they can add it to the report section and a system can find the person that made that code and auto tag him as a cheater or "solution giver". Then if during the contest anyone submits the same code it can also auto flag them as cheating. (I also think this shouldn't apply to problems with a really simple solutions such as problems A since code there is often almost completely identical). If the Codeforces team implements this, I think it would help reduce cheating.

2. Cheating blogs don't do anything: After every single contest there are multiple blogs talking about cheating for the next 2-3 days. They don't do anything to help. People exposed for cheating often keep on cheating and the only thing those blogs accomplish is annoy non-cheaters. The solution I proposed above would solve this problem and give people an official method of reporting cheaters. I also read this blog today and while the poster has his heart in the right place I don't think this would do much to help. Especially since it even has a Famous Cheaters section which goes to show how little blogs actually do to help with the underlying cheating problem. Another concern of mine in situations like this is false positives. In the comment section there were already arguments about whether or not someone was a cheater. For that reason blogs about cheating do more harm to the community than help.

3. Cheating: This bit is for the people cheating. Cheating does nothing to help you. There are many reasons someone might want to cheat. You might want to show off to your friends, you might want to have a high rating to use it as a selling point at a job interview, you might think it'll help you get into university/collage if you have a high rating and add that to your application. But in the end it forms who you are, if you take the easy route and cheat you won't accomplish anything. If you show off to your friends with an unearned rating you aren't the best friend and I think your friends would agree if they were to find out about you cheating. If you need it for a job interview, think about what happens if you get the job, what happens when you face difficult problems at work and can't simply copy someones solution? If you've always taken the easy way and suddenly can't you won't last long at that job. The same goes for university/collage. Higher education is hard, much harder than competitive programming and the punishment for cheating there could ruin your life/plans if you get caught. Don't take the easy way, struggle though improvement like everyone else. You'll thank yourself for it in the end.

4. Final thoughts: At the end of the day cheating will always exist for whatever reason someone thinks they have to cheat. The best thing you can do is focus on your own improvement. Rating means nothing, your abilities is what matters. You might have a bad contest and lose rating or get a lower rating due to mass cheating, but that doesn't change what you can and can't do. If you improve your rating will also improve regardless of what others do.

Thanks for reading!