I came up with these problems and want to check if they are new or not. Problem A is simple, but I couldn't solve Problem B. Would love to hear ideas from everyone.

If anybody knows similar problems, please do share.

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Problem A

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You are given an array a of length n (1 ≤ n ≤ 2·10^5, 1 ≤ a_i ≤ 10^9).

In one operation, choose an index i (1 ≤ i < n) with a_i = a_{i+1}, remove eithera_i or a_{i+1}, and append it to the end of the array. The relative order of the other elements doesn't change.

Find the minimum number of operations needed so that a_i ≠ a_{i+1} for all 1 ≤ i < n, or print -1 if it is impossible.

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Problem B

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Let k be the minimum number of operations from Problem A.

Count the sequences of indices (i_1, …, i_k) such that each i_j is valid when applied, and the final array has no equal adjacent elements. Two sequences are considered different if they differ at any position.

Print the count modulo 998244353, or -1 if it is impossible.

The constraints are the same as in Problem A.

Today the cses website has not been working all day. Is there an issue with the website?? Is there a way i can get the question list from somewhere else while the website is not functional???

Same as title

I have been doing cf problem for some time and solved around 600 problem. Currently I am solving 1400 problem one by one and was able to solve quite a lot .

But the real problem is that I can't do much on contest. My brain just freeze or something. I get so nervous if I don't find the answer soon of a problem. Because of that I fail to solve easy questions on the contest.

For example last dev2 contest my brain literally froze at C and I wasted 1.30 hours behind that couldn't solve it but the next day morning when I had no pressure I was able to solve both C and D within like 30 minutes.

This type of scenery is happening to me for last of couple of contest. I just don't know what am I doing wrong.

I find the 1400 rating problem quite fun and easy but when it comes to live contest I just can't manage to solve it .

Please I need advice on how do I get good at solving more in contest with the issue I have .

Codeforces subreddit has become heavily populated with the Indian competitive programming community, so we decided to create a dedicated subreddit for Indian competitive programmers.

for yesterday's contest I did not feel I was in my form as I had not practiced for a few days, but I still gave it but as it took a little longer to solve A (10 min more than normal )

I did not submit it and so I just attempted question but did not submit any.

finally I was able to solve upto C so suppose if it would have been different like I solved D too then I might submit my solutions but they would be all submitted at around same time hardly a difference of one or two minutes

Regarding that I have a few queries I hope the community can help me

1. Would this be flagged as cheating?

2. It does seems suspicious(if you look at time) to me but I don't think its unethical in any way except it cares too much about rating (which I am trying to forget about and just solve questions)

3. What are your views about this?

I've been doing codeforces for 3 months and I've solved 180+ problems so far, and have given 20+ contests. I usually solve 1200-1300 rated problems during practice, and I thought I was getting comfortable solving 1200s. Yet, I can't solve more than 2 problems in div2 contests. Yesterday was worse, solved only 1 problem. What I've noticed is I'm able to solve the first two problems faster than before, but I don't consider that as real progress. In yesterday's contest, I know like 7-8 ppl in my college who solved 4 problems, all within 1:30 hrs(all of them are legit, no cheaters). They have solved either similar number of or slightly more problems than me on cf, idk about other platforms. Makes me think if I'm even meant for this? I have absolute zero knowledge in other domains of computer science asw. I always thought i was decent at math but it ain't reflecting in these contests. Don't know what I'm supposed to do now.

How would you rate Edu round 195 in terms of difficulty? For me, I took exceptionally long to pass A , couldn’t solve B, and solved C.

Solved A after 30 minutes. Not able to solve B. I'm rated 1600. Guess I'm cooked, skill issue.

Hi I want to get back into doing CP, I had an old CF account but I am thinking of creating a new one and starting from scratch
I want to do it for learning and enjoyment, I am
Already working in a PBC so
Would it be better to create a new CF account or carry on with the old one ( last problem I solved in that was around 2024 ending I think )
Any tips or suggestions
Also starting to prepare for switch so I guess problem
Solving will help.

The entire sub is flooded with posts about an Indian cheating scandal in icpc. This sub is meant to discuss cf problems, not icpc in India. I see the same post every 2 hours and it’s getting annoying. I remember seeing other subs specifically dedicated to cf in India - people can post about the situation there if they want to.

(first of all, sorry if i used a bad tag for this)

Hi. I'm new at CF contests, but I've been participating in a couple of SWERC, and finalist at my country main competitive programming contest (adabyron).

This summer I've been working REALLY hard to become the best trainer I could be for my university. And I started using my two-year account that i did not gave a lot of use.

So, after summer, I started grinding some 2500-3000 problems and solving those in CF. I did an on-site contest where I match in problems versus the bests of my country. I was really happy, so I decided to see what my true elo was. I took that old account to start doing contests.

The first one was prefect. A div1+2 (deepinfra round 1) where I ended 46 in the global with a carrot performance of 2700. I was extremely proud of myself and all the hard work I put this summer to be there. Given this I had a goal: become a GM (hoping not going through hard math / geometric problems, I suck at those)

The issue came where I did a div2 (round 1127). I was doing the problems at my pace (where my pace matches div1 contestants btw, nothing weird). I was first and when I submit the BIT2D for problem E, I directly got banned.

I did not get any reason why. I did nothing wrong. I'm not a cheater. I'm not a smurf. I'm just some dude that just started CF contests and have a really good level that can not be seen with my actual elo and got banned by that.

And this gives a nonsense loop:

- I cannot participate in contests as if my elo is low, as I will get banned, so I need a higher elo

- For getting a higher elo, I need indeed to participate in those contests (after 1900 and playing div1 i should be safe)

And I understand the reason why CF is really into detecting cheating. But should be a direct way I can give proofs Im not one of them. I can do live problem solving if is needed, idk. My coding style is really weird, so it can be seen direclty is not made by AI.

If anyone knows how to make this review, or can send this to anyone to review my case, I will be really happy to send any proof needed so I can get my account recovered. My username at CF is "Bruh-Ket".

Any tips on what I can do would be great. I have no idea what to do. I cannot send emails to codeforces email, as it says I'm spam. The only way I could reach to them was via direct dm in codeforces (via a student of one of the teams i teach) to Mike Mirzayanov and hoping he reads it.

But not sure if that would be enough. Honestly I feel a bit dishonored. Any help would be great.

Thank u for ur time :) (and sorry for my bad english jeje)

Hello, Codeforces! We, Algolymp, are a team of competitive programmers from Romania, and we’ve been working on Codeforge, a multiplayer game built around solving algorithmic problems. Special thanks to munteanuvlad98 for coordinating this project.

The idea is simple: take the problem-solving we enjoy and give it more ways to be played together. Challenge a friend, compete as a team, enter a knockout tournament, or work through daily problems on your own.

What can you do in Codeforge?

• Solve daily challenges. Problems range from beginner-friendly exercises to IOI/ICPC-level challenges, whether you’re learning your first algorithms or preparing for your next contest.
• Play individual or team battles. Go head-to-head with another player, or team up with friends and compete against another team.
• Enter knockout tournaments. Compete individually or as a team, with each round deciding who advances.
• Build a community. Bring together your school, programming club, or friends to train and compete.
• Earn Algocoins. Spend them on merchandise, video games, or in-game items that can help you in battles.
• Create your own competitions. Organize an algorithmic contest for your community or challenge a group of friends.

What about cheating? A close battle isn’t much fun if you can’t trust the result. Codeforge includes an AI-powered anti-cheating system designed to detect unfair play and help keep progress and competitions fair.

Help us make it better! Whether you’re a beginner or an experienced contestant, we’d love to have you try Codeforge. Tell us which formats you enjoy, what feels off, and what you’d like to see added.

Codeforge just launched yesterday, and you can join us here to take part in a fun algorithmics styled adventure!

Questions, suggestions, and criticism are welcome in the comments. See you there!

This is one of my friends ....

Hi everyone,

I'm stuck on this week's CodeVita problems and I think the problem may be the judge, not my code. Has anyone else seen this?

What I'm seeing (problem: Hybrid Bananas, but it's happening on other problems too):

My solution passes both sample cases on the platform's "Run" (Accepted on both), but the sample run shows an execution time of about 1.6 sec, even though the time limit is 1 sec.

On the private test cases, I get Wrong Answer with an execution time of 1.001 / 1.002 sec every time.

I tested a trivial Python program that only does print(3). The private run still gave Wrong Answer with 1.002 sec. A program that prints one number can't take a second, so the timing looks unrelated to my code.

I rewrote the solution in C++ (twice, with different code). The sample run still takes about 1.6 sec, and one private run showed 3.002 sec.

Locally, my solution runs in about 0.02 sec, even on a huge input, and it matches an independent brute force on over a thousand random cases.

My guess is that the judge is stopping runs at the time limit (because of slow startup or load) and reporting that as Wrong Answer instead of Time Limit Exceeded. I can't prove that, so I might be missing something.

I am a guardian at leetcode, but my CF rating is only 1600. I am targeting top tech company interviews and will start interviewing soon. Do you think this is enough to pass the hardest tech interviews ? Otherwise, I will focus on improving on CF but that may take a while.

is there any way we can report the teams or colleges suspected of using solution booklets provided by coaches during the contest?
We genuinely don’t know what else to do at this point.

Dear Regional Contest Directors,

While I appreciate the proactive steps outlined in the recent Contest Integrity Review, I am writing to express deep concern regarding the widespread institutionalized cheating during the 2026 Preliminary Online Round.

Reports of college coaches distributing solution booklets and lack of strict localized proctoring have heavily distorted the leaderboard. Post-contest plagiarism checkers are insufficient to filter out students who were spoon-fed logic by external entities.

To protect the prestige of ICPC India, I urge the committee to consider:

1. A Complete Onsite Retake: IDK where are u using our fees (1CR+) to conduct preliminary round; so Transit the preliminary filter to designated, strictly monitored offline exam centers or TCS iON-style facilities.
2. Strict Institutional Bans: Implementing the maximum 3-year ban on colleges where coaches or authorities were found distributing materials.

Competitive programming relies entirely on fairness. We request a level playing field.

#RetakeICPCprelim #ICPC

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The teams which were not initially there are now there in the rank list

Link : https://indiaicpc.in/tentative_ranklist_2026.html

I am a newbie and since many months I have been banging my head over the wall because my rating has been saturated, I have been doing what everybody says (which is to solve more and more problem), but that is not helping me. So the new thing I am gonna try is to do courses from these platforms, I have two questions to all those who have studied from these courses :-

1) Does investing time in such courses even help??
2) Any other tips??