Hello Codeforces!

The series of Educational Rounds continues thanks to the support of the Neapolis University Pafos.

On Apr/03/2025 17:35 (Moscow time) Educational Codeforces Round 177 (Rated for Div. 2) will start.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 problems and 2 hours to solve them.

The round is based on the problems from the Open Championship of Karelia in competitive programming.

The problems were invented and prepared by Galina Galina_Basalova Basalova, Valentin Valentin_E Ermishin, Lev robotolev Provotorin and me.

I would like to thank the authors of the championship problems whose tasks were not included in the final set for the round: Ruslan r314 Alkin, Yuriy basalov_yurij Basalov, Alexey ashmelev Shmelev, and Nikolay Nicola95 Ermolin.

I would also like to express my sincere thanks to the round coordinators: Ivan BledDest Androsov and Mikhail awoo Piklyaev for improving the quality of the problems and helping with their preparation.

Big thanks to our testers: Brovko, deni1000, KIRIJIJI, shnirelman, Alenochka, slash0t, LightSky, infinite_meltdown, Knh_era, M1chail, Antithesis, Kolychestiy, neohacker for their valuable advice and suggestions!

And of course, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

Our friends at Neapolis University Pafos also have a message for you:

Admission to the Computer Science and Artificial Intelligence bachelor's program at Neapolis University Pafos is open!

The JetBrains Foundation supports this bachelor's program and offers 20 fully funded scholarships for talented first-year students. They initially announced 15 scholarships but have now increased the number to 20 to give more students the opportunity to join the program.

Each scholarship covers entire duration of the program, including tuition, accomodation, medical insurance, visa fees, and €300/month pocket money.

They are also offering now 2 fully funded scholarships for students transferring into the second year of the program.

First admission round:

• Application deadline – April 23, 2025
• Entrance test – April 27, 2025

UPD: Editorial is out

Hello, Codefoolers!

We, AlperenT, flamestorm, prvocislo, temporary1, ToxicPie9, and -1e11, would like to invite everyone on Codeforces to April Fools Day Contest 2025! The 13th April Fools Day Contest will take place on Apr/01/2025 17:35 (Moscow time). This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.

In this round, you will be given $$$n$$$ problems where $$$\sum\limits_{x=1}^{\infty} \frac{1}{x^n}$$$ converges and 2 hours to solve them. The contest will use extended ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces, unless the problem says otherwise.

Please note that the round is unrated and that the penalty for a wrong submission is 10 minutes.

To get an idea of what the contest will look like, you can check out the contests of the past years: 2012, 2013, 2014, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024

Thanks to our precious testers (they exist, trust me):

Please do not bother sending clarification requests in the contest as we obviously do not enjoy sending funny responses like we did in the last two years. It is definitely not the most fun part of April Fools.

Lastly, we have a video editorial this year (Russian captions available)!

Good luck, and have fun!

Edit 1: Editorial is out!

Edit 2:

Congratulations to the winners:

1. ksun48
2. Madball
3. iakovlev.zakhar
4. tiger2005
5. errorgorn

And the first solves on each problem:

• A: vladimirfilip
• B: Auchenai01
• C: Dark (after AprilFoolsClairvoyant)
• D: koishi.komeiji
• E: jiangly
• F: tiom4eg
• G: BucketPotato
• H: N/A (but circle977 got closest with every word except 10th)
• I: SeptaCube
• J: fishy15 (initially conqueror_of_tourist, but got hacked after the contest)

Xin Chào, Codeforces! (☆^ー^☆)

We are thrilled to invite you to participate in Codeforces Round 1014 (Div. 2), which will be held on Mar/29/2025 17:35 (Moscow time).

This round will be rated for all participants with rating below 2100. Participants with higher ratings are encouraged to participate out of the competition.

You will be offered 6 problems and 2 hours to solve them. The tasks were authored and written by k1sara and sergeev.PRO. We hope you enjoy the challenge!

A heartfelt thank you to everyone who made this round a reality:

• 244mhq and Um_nik for expertly coordinating the contest and offering invaluable guidance throughout the process,

• makrav, zltzlt, IzhitskiyTimofey, sadness, Noinoiio, max0000561, Vash_nick, yunetive29, ItsNotMeItsYou, DimonKrutoi, dope, Fu2o, Mikhango, re-wa-tl-ok, VictorKleymenov for testing our round and providing impactful feedback,

• danya111 for coming up with some exceptionally riveting excuses as to why he’s too busy to test our round,

• sergeev.PRO for being an amazing co-author, for putting up with my endless complaints, and for generously letting me copy every math homework over the past five years,

• MikeMirzayanov for the fantastic Codeforces and Polygon platforms.

• You for participating in the round.

[UPD 1] The score distribution (now changed) will be as follows:

[UPD 2] EDITORIAL

[UPD 3] Congratulations to the winners!

All participants:

1. ksun48
2. potato167
3. arvindf232
4. conqueror_of_tourist
5. maspy

Rated only:

1. namcartoon06
2. Milashka
3. chanshin9211
4. IuNgocBich
5. abhaydixit500

Greetings, Codeforces Talents!

We are thrilled to invite you to Teza’s first Codeforces competition!

Teza, founded in 2009 as a high-frequency trading firm, has evolved into a leading systematic quantitative hedge fund. From equities to options, futures, and crypto, we transform complex mathematical concepts into financial strategies that operate across the world's largest markets.

Our team is composed of some of the brightest minds in the industry, including International Olympiad winners in Physics and Mathematics, and the youngest individuals ever to earn double Ph.D.s in Computer Science and Physics from MIT. Our CEO, Misha Malyshev, a MIPT graduate with a Ph.D. from Princeton, is known for setting an unbeaten world record for returns on capital on Wall Street. Learn more about Misha.

We have a team member who has discovered a new star, highlighting our commitment to pioneering exploration in all fields. We believe that only exceptional minds make markets efficient.

Good luck to all participants! And for those not competing, thank you for stopping by — if you're passionate about technical and algorithmic challenges, solving Olympiad-style problems as your day-to-day job, we’d love to connect.

Check out our career opportunities here and explore where your skills can take you.

Enjoy the competition and happy coding!

Hello, Codeforces \[^-^]/

The competitive programming laboratory of the IT campus NEIMARK from Nizhny Novgorod is pleased to invite everyone to participate in Codeforces Round 1013 (Div. 3), which will be held on Mar/25/2025 17:35 (Moscow time).

The round is based on the problems of the final of the first olympiad by IT campus NEIMARK. 312 students from 28 subjects of the Russian Federation took part in the olympiad. And at the final competition, in addition to Nizhny Novgorod students, we met finalists from the Chuvash Republic, Moscow, Tolyatti, Kirov, Saransk and Ulyanovsk.

If you participated in the final of this olympiad, please refuse to officially participate in this round.

The topics of the tasks will be related to the working days and weekends of our laboratory. The laboratory has existed for a little less than a year, but during this time several training camps, many personal and team trainings have been held, and dozens of tasks for school and student competitions have been developed (you can find some of these competitions in the section Gym). We opened competitive programming clubs in schools in Nizhny Novgorod, and began training interested IT teachers. We also acted as a venue for several programming competitions.

And at Mar/25/2025 17:35 (Moscow time) we will finally share with you one of the most important results of our work.

You will be given 7 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for the wrong submission in this round is 10 minutes.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Remind yourself that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

• take part in at least five rated rounds (and solve at least one problem in each of them).
• not have a rating of 1900 or higher at any moment in time.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

We hope you will enjoy problems! The tasks were prepared by our laboratory staff: Alexey ashmelev Shmelev, Islam l-_-l Shayakhmetov and Diana Diall_ Alyaseva.

Thanks to MikeMirzayanov for the CodeForces and Polygon systems. Thanks to Vladosiya for the coordination and help in preparing the round.

Thanks to our testers: MForest, OG_Matveychick1, Tmitmi, Riladavin, quaha, eepsilon, anotherworld, konred, NerfThis, gtheoden42, sasha00123, ReshuVse, artem., OG_Sergzhick2, bugrova, Itsmylove1

Good luck for everyone and praise the sun \[^-^]/

Upd. Editorial

There will, and there shall be a THU round!

Nihao Codeforces! After the unfortunate event which led to Codeforces Round 1010 (Div. 1, Unrated) and Codeforces Round 1010 (Div. 2, Unrated) being unrated last week, we’re back and stronger than ever!

Tsinghua University’s Student Association of Algorithmic Competitions (THUSAAC) is pleased to invite you to participate in Codeforces Round 1012 (Div. 1) and Codeforces Round 1012 (Div. 2) on 23.03.2025 08:35 (Московское время). This round will be RATED for everyone. You will be given 2 hours and 30 minutes to solve 5 problems for division 1 and 6 problems for division 2, and two of each will have subtasks. Note the unusual time of the round.

Our team of amazing problem setters include: Iam1789, Ecrade_, E.Space, QuietBeautifulThoughts, gyh20, SpiritualKhorosho, dapingguo8, myee, abruce, _Lucien. Some of the problems prepared were not used in the final contest but we would still like to thank them nonetheless.

We would also like to express our gratitude to the following individuals:

• KAN for helping to host the round;

• FairyWinx for coordination and helping with the problem preparation;

• The team of problem setters for crosschecking the problems and also donghanwen, SnowySummer, wangjinbo, xiaoziyao, turmax, SomethingNew, teraqqq, temporary1, LeoPro, gmusya, KiruxaLight, 18o3, mz1 for testing the contest and providing us very useful feedback;

• Tsinghua University’s administration, especially our advisor Wentao Han for helping us in all means possible to ensure the smooth organisation of the whole THUPC event;

• MikeMirzayanov for the amazing Codeforces and Polygon platform!

THUPC is an annual event hosted by Tsinghua University’s Student Association of Algorithmic Competitions. It is the largest student-run competitive programming contest in China with the top 100 Competitive Programming teams from all over China coming onsite to vie for the crown of BEST CP Team in China after qualifying from a pool of 1000+ teams.

We hope you will enjoy and have fun in the contest. Good luck.

UPD: Here comes the scoring distribution.

Division 1:

Division 2:

UPD2: Congratulations to the winners!

Div.1:

1. tourist

2. ecnerwala

3. jiangly

4. ksun48

5. JDScript0117

Div.2:

1. liudiao

2. lnw143

3. ilovelll

4. boboquack

5. Madeeyuth

UPD3: Editorial

Hi Codeforces!

I Serval am glad to invite everyone to participate in Codeforces Round 1011 (Div. 2), which will be held on 22.03.2025 17:35 (Московское время).

This round will be rated for participants with rating lower than 2100. We will be glad to see the participants with a higher rating to take part in our round unofficially as well!

You will be given 6 problems to solve in 2 hours, one of which will be divided into two subtasks. Scoring distribution will be announced later.

I would like to thank everyone that makes this round possible:

• Error_Yuan and satyam343 for coordination of the round and help with the preparation. It is noteworthy that this round is the debut of Error_Yuan as the coordinator. Special thanks to him!
• 18o3, AG-88301, Dominater069, Edeeva, Graythron, Hanghang007, JagguBandar, Friedrich, N_z__, Nerovix, Proof_by_QED, RDDCCD, RTE, SSerxhs, SkyWave2022, SpyrosAliv, StarSilk, _istil, chromate00, darkkcyan, guangmingzhengda, larush, macaquedev, mathtsai, temporary1, tiger2005, yoru_sacri for testing the round and providing valuable feedbacks.
• Alexdat2000 for Russian translations of the problemset.
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• You, for participating in the round and gaining a positive delta.

Good luck & Have fun! (∠・ω < )⌒☆

UPD: Scoring distribution: 500 — 1250 — 1250 — 1750 — 2500 — (2000 + 1000).

UPD2: Editorial is out. Congratulations to the winners!

Div. 2:

1. sounansya
   DuyNgaDocTon1410 Disqualified.
2. SoloRE
3. nocap
4. Asbjorn
5. AksLolCoding

Div. 1 + Div. 2:

1. potato167
2. A_G
3. arvindf232
4. antontrygubO_o
5. TKT_YI

Hello, Codeforces.

The XIII BSUIR Open Programming Championship will be held from March 17 to May 3, 2025 (Minsk, Belarus).

Registration is already open and available until March 20 (inclusive). Teams consisting of 3 students from one higher educational institution, as well as school teams from different educational institutions are allowed to participate. Registration is made by the team captain on the website acm.bsuir.by.

The competition will be held in several stages:

• March 17 — 24 — Qualifying round (in absentia, mandatory for schoolchildren and students of BSUIR)
• April 9, 14:00-19:00 — Semi-final (in person, at sites organized by educational institutions)
• April 26 — Student final (in person, Minsk, BSUIR, Building 4, 9 Gikalo Street)
• May 3 — School final (in person, Minsk, BSUIR, Building 4, 9 Gikalo Street)

More information about the upcoming Olympiad and registration can be found on the website acm.bsuir.by.

Some previous videos:

• BSUIR Open XII Student 2024
• BSUIR Open XI Junior 2023
• BSUIR Open X Student 2022