Hi everyone!

A week ago, the 2nd edition of the Western European Olympiad in Informatics was held in London, UK, and now we've brought the problems for everyone to solve on Codeforces! The mirror contest will be held on the Codeforces Gym on Sunday $$$14^{\text{th}}$$$ July 2024 at 10am UTC+1 (check your timezone here!).

Please don't participate in the mirror contest if you have participated or seen the problems!

The Western European Olympiad in Informatics is an individual contest for top secondary school students from Belgium, France, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Switzerland and United Kingdom.

The contest consists of a single day; contestants are given 5 hours to solve 4 problems of various difficulty. Each problem is worth 100 points, distributed into multiple subtasks with different constraints that allow the participant to earn partial scores. For testing, the IOI grading format is used, where the participant receives full feedback about the execution of the solution on all tests during the contest. C++ is the only allowed language in this contest.

We hope you enjoy the contest!

• WEOI 2024 Committee & Contributors

FelixMP hugopm I_love_MikhailRubinchik ScarletS veluca93, Ahmadsm2005 Bakry erekle

Hello, Codeforces! We are pleased to invite you to Codeforces Round 957 (Div. 3), which will be held on Jul/11/2024 17:35 (Moscow time).

The round will be hosted by rules of educational rounds (extended ICPC). You will be offered 7 problems, which I with Noobish_Monk, ErnKor, Kmes and ArSarapkin have prepared for you.

The rules of the third division are:

• The penalty for a wrong submission is 10 minutes.

• 12-hour phase of open hacks after the end of the round (hacks do not give additional points)

• after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated.

Reminding you, that only trusted participants of the third division will be included in the official standings table. This is a forced 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),

• do not have a point of 1900 or higher in the rating.

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

We would like to thank everybody, who helped in preparing this round:

• Our coordinators, Gornak40 and Vladosiya for a wonderful coordination!

• MikeMirzayanov for wonderful Polygon and charming Codeforces!

• Vladosiya for deleting the lore in almost all of the problems...

• Our numerous testers: natalina, FairyWinx, Kosya, ErnKor, 74TrAkToR, ArSarapkin, mainyutin, senjougaharin, gaiercop, mikeamir0310, Maksim_Musikhin, Arina77, artimovich.ko, main-scobik, savanzh, petr_davydov, Pronkin_dv, kalita.georgy, kuznetsov.da, s_w_a_n_i_k, Keopint, VolkovMA, kuewa, cry, Harsh_kunwar, Kon567889, dshindov, OAleksa, SajidAbdullah, fishcurry, george_the_piggy, k1sara and many others, who didn't mention their handle.

• Special thanks for KEFedorov, for inviting more than 35 testers.

Good luck!

UPD1 After the end of the round, Shayan will broadcast the solutions, a recording will also be available, but we will also prepare a textual editorial.

UPD2 Video Discussion by Shayan

UPD3 Video of solving the round + Editorial by the "winner" of this round, neal

UPD4 Editorial.

UPD5 Congratulations for the winners:

Official:

1. siiiuuuuuuu

2. shil_pelmen

3. xiojoy

4. _Separation

5. son_and_moon

Official + Unofficial:

1. tourist

2. neal

3. Dominater069

4. abc864197532

5. hitonanode

Hello, Codeforces!

NJACK — the Computer Science Club of IIT Patna is excited to invite you to Codeforces Round 956 (Div. 2) and ByteRace 2024 under Celesta — the annual Techno-Management Fest of IIT Patna.

The contest will take place on Jul/07/2024 17:35 (Moscow time). This round will be rated for participants with rating lower than 2100.

Many thanks to all the people who made this round possible:

• The problems were authored and prepared by AwakeAnay, ShivanshJ, TimeWarp101, DC17, BlazingDragon, Swap-nil, Pew_Pew. and me.
• Special thanks to ScarletS for coordinating the round (and not killing me)!
• A big shoutout and thankyou to Alexdat2000 for providing the Russian translations.
• Thanks 2.0 to ScarletS for having improved the experience of other CF users over the years.
• Special mention to mayankfrost and quantau for their guidance and moral support.
• A_G, Andreasyan, maomao90, CSQ31, fishy15, eggag32, MateoCV, Evirir, bananasaur, satyam343, jat.arc2004, chromate00, hashman, Nishant_K, Ali_cs7, Patel45, Newtech66, CIXTEEN, braman, 7oSkaaa, Edward4762, LucaLucaM, waidenf, yoyo0869, priyanshu.p and ishaandas1 for testing and providing detailed feedback that improved the quality and balance of the round significantly.
• Our lord and saviour MikeMirzayanov for great systems Codeforces and Polygon.

You will have 2 hours 15 minutes to solve 7 problems.

UPD: Scoring Distribution: 500 — 1000 — 1250 — 1750 — 2000 — 2500 — 3000

UPD: Editorial

UPD: Congratulations to the winners!

Top 5 (Div 2):
1. _worst_
2. Shirayuki_Noa
3. cynNYCal
4. cocae
5. _furina

Top 5 (Div 1):
1. neal
2. jiangly
3. BurnedChicken
4. turmax
5. Sugar_fan

About Celesta

Celesta is the annual Techno-Management Fest of IIT Patna. Celesta conducts a variety of events in various technical domains. Some of these are open and free for all, with exciting prizes and goodies for the winners!

You can head over to our website and check it out for yourself!

We have had the 2023 edition of ByteRace hosted on Codeforces too. Feel free to have a look: Codeforces Round 845 (Div. 2) and ByteRace 2023

Good luck!

Hi, Codeforces!

We are pleased to invite you to EPIC Institute of Technology Round Summer 2024 (Div. 1 + Div. 2), which will be held on Jun/30/2024 17:35 (Moscow time). You will be given 8 problems, two of which are divided into two subtasks, and you will have 3 hours to solve them. The round will be rated for everyone.

At least one of the problems will be interactive, so please read the guide for interactive problems if you are not familiar with it.

We would like to thank:

• errorgorn for coordinating the round.
• Geothermal, turmax, noimi, SomethingNew, feecIe6418, Endagorion, glebustim, zeliboba, thanhchauns2, zengminghao, mwen, cristi_tanase, milind0110, CSQ31, Evirir, AkiLotus, htetgm, TrendBattles, GreatEagle, chromate00, Valenz, Vamperox, priyanshu.p, DOCUTEE, Tran_Thi_Thanh_Van, and tibinyte for testing the round and providing useful feedback.
• MikeMirzayanov for Codeforces and Polygon.

We hope you'll like the problemset!

UPD: The score distribution is 250 — 750 — 1000 — 1500 — 1750 — (2000 — 500) — (3000 — 2000) — 5000

UPD2: Editorial

UPD3: Congratulations to the winners!

1. Radewoosh
2. ecnerwala
3. tourist
4. Benq
5. gamegame
6. ksun48
7. maroonrk
8. JoesSR_
9. Maksim1744
10. ugly2333

And now, a few words from today's sponsor!

About EPIC Institute of Technology

EPIC Institute of Technology is an innovative educational project, driven by the Deltix team under the EPAM Systems umbrella. As part of EPIC — EPAM Product Innovation Center, we aim to cultivate the brightest minds and prepare them for a future in cutting-edge technology projects.

Why EPIC:

EPIC Institute of Technology is an accelerator for the best talents. Our students will acquire hands-on experience in one of the selected major programs, all of which are highly demanded right now on top projects, together with the fundamental knowledge, so indispensable for real professionals. Successful graduates will have a unique chance to jumpstart their career on the most challenging and interesting EPAM projects worldwide. You will join the community of intelligent and driven individuals and have an honor to work with and learn from them.

Here are the answers to the most common questions:

How much does education cost?

EPIC Institute of Technology is completely free. There are no fees to register for exams, tuition fees or any other hidden liabilities. The only restriction for getting into EPIC Institute of Technology is age. You must be older than 18 years old to become a student.

How is the educational process organized?

Each program lasts exactly one year. The academic year consists of two semesters. Courses in the first semester are the same for all programs. Courses in the second semester depend on the selected major program.

During the semester, students complete homework assignments and take 2 exams—a midterm and a final. The final grade a student gets for each training course depends on the quality of completed assignments and participation in practical classes.

How will the classes be held?

Lectures will be pre-recorded and available for self-study. Practical classes will be held at the specified time according to the provided schedule. Also, students will have an access to a Discord server, where they can discuss topics of academic interest with teachers and other students.

In what language will I study?

All programs are in English.

How can I apply?

The admissions process is as follows:

1. Fill out the form on the website.

2. Take part in one of the entrance exams that will be held in our Codeforces group. You can also find past exam breakdowns there, which may help you in your preparation. Exam dates will be announced later, so stay tuned to the announcement channel and our LinkedIn group.

3. If you successfully pass the exam, you will receive an invitation email.

What will happen after graduation?

All EPIC Institute of Technology graduates will get a diploma and the best students will be offered to join, either as an intern or a full-time position, one of the hot EPAM projects where skills acquired at EPIC Institute of Technology will be demanded.

Please visit our website to learn more about EPIC Institute of Technology and the available programs. If you have any questions, you can quickly ask them in our chat.

Hello Codeforces!

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

On Jun/27/2024 17:35 (Moscow time) Educational Codeforces Round 167 (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 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Adilbek adedalic Dalabaev, Ivan BledDest Androsov, Maksim Neon Mescheryakov, Roman Roms Glazov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

UPD: Editorial is out

Hello, Codeforces!

It's been a long journey, and I'm finally pleased to invite you to participate in our Codeforces Round 955 (Div. 2, with prizes from NEAR!), which will take place on Jun/25/2024 17:35 (Moscow time).

This round will be rated for all participants with a rating is below 2100. Participants with higher ratings can participate out of competition.

During the round, you will need to solve 6 problems. You will have 2 hours to solve them.

The problems for the round were prepared by nik1998, egor4444ik, iamdimonis and me.

We sincerely thank everyone who provided invaluable assistance in preparing this round:

• Our insightful coordinator 74TrAkToR for excellent communication, helpful advice and assistance in problem preparation!
• Kolychestiy for improving one of the problems.
• EJIC_B_KEDAX, A_G, zwezdinv, Dominater069, culver0412, TheScrasse for red testing.
• Kolychestiy, CSQ31, exhausted, azureglow, harsh__h, meowcneil for yellow testing.
• onlytrall, veleboks, zarubin, robotolev, TimVen74, Vladosiya for purple testing.
• Alenochka, LightSky, Chugunov_Alexander, slash0t, PoDuReMaN, katzi, Vamperox, redpanda for blue testing.
• Matrosk1n, bessarab, dariasaligina, GRIVA_, viteli, dazlersan1 for cyan testing.
• Kirillar2, Sonya_2009, dan00ile for green testing.
• venlesN for gray testing.
• MikeMirzayanov for the wonderful Codeforces and Polygon systems.

We are pleased to announce that NEAR has supported the round!

NEAR was founded in 2017 by Illia Polosukhin, one of the creators of Transformers, and Alex Skidanov as an attempt to build an artificial system capable of solving competitive programming problems. You can read more about that attempt here.

Ultimately, NEAR pivoted into building a blockchain protocol, which it launched in 2020.

This year, NEAR started NEAR.AI, a new lab with a mission to build AI systems that are open and available to everyone, instead of being controlled by a few mega-corporations.

One of the areas of focus is making models capable of reasoning reliably, and for that, competitive programming problems provide a great environment. To help us build it, we invite all the Russian-speaking members of the Codeforces community with a rating of Specialist or higher (1400+) to help us annotate step-by-step explanations of solutions to competitive programming problems. We want to annotate a very large set of problems of all difficulty levels, and pay relatively high rewards in NEAR per annotation. Don't speak Russian but speak English? Stay tuned here, we will be launching the same project for English-speaking people very soon, and will likely sponsor another round when it happens.

The round also features prizes in NEAR. Participants who rank in the top 16 will receive Ⓝ 16 each. The next 32 participants in the overall ranking (including unofficial participants) will receive Ⓝ 8 each. The following 64 participants will receive Ⓝ 4 each; the subsequent 128 participants will receive Ⓝ 2 each, and finally, the next 256 participants will receive Ⓝ 1 each.

Additionally, 64 random participants from the top 4096 in the overall ranking will each receive Ⓝ 4.

Score distribution: $$$500\,—\,1000\,—\,1000\,—\,1750\,—\,2500\,—\,3000$$$

Wishing everyone good luck and high ratings!

UPD: Let's continue the series of announcements with a photo of the authors :)

UPD 2: Editorial!

UPD 3: Congratulations to the winners!

Div 1:

1. tourist

2. jiangly

3. SSerxhs

4. kizen

5. potato167

Div 2:

1. lunchbox

2. _JiaY19_

3. gxy001

4. _DongY19_

5. Muelsyse_sep005

UPD 4: Wonderful video analysis of A-E tasks. Thank you, Shayan!

Hello! Codeforces Round 954 (Div. 3) will start at Jun/23/2024 17:50 (Moscow time). You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.

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.

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.

Remember 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)
• do not have a point of 1900 or higher in the rating.

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.

The tasks were created and prepared by 74TrAkToR. I would like to thank everyone who helped me a lot with round preparation.

• Coordinator Vladosiya for excellent communication and brilliant coordination of the round!
• Testers veleboks, iNNNo, Sk0rlupka, sharkycode, Noobish_Monk, meowcneil, Matrosk1n, sumit_kk10, Sonya_2009, FelixArg, KirillKhalin, viteli, zwezdinv, EJIC_B_KEDAX, _why_not_, detective...dots, Leeda, windreaper for high-quality testing and valuable advices!
• MikeMirzayanov for amazing Codeforces and Polygon platforms!

Good luck!

UPD: Editorial

UPD: Video Editorial

This weekend, we will host the 2nd Universal Cup Semifinal. Unlike with previous Universal Cup rounds, there will be exactly one window that all teams will participate in. This window will be from 5pm to 10pm UTC+8 on Sunday, June 23rd. Note that this window is after the onsite version.

Any Universal Cup registered team can participate. If you are new here, please register following the instructions on Registration.

Besides competing to advance to the Universal Cup Finals, sponsored by Huawei, we have also prepared prizes for teams in the top 10 (excluding onsite teams in the Summer Summit) . The prize details are as follows (may be replaced by products of similar value):

After the online semifinal, we will host a stream of all onsite teams competing in the Semifinal at the Summer Summit event in Cancun, along with problem analysis. The stream will start immediately after the end of the online version at 10pm (UTC +8) and end at 3am (UTC +8). We will run livestreams in English and in Chinese as follows:

• English: YouTube through tourist's account!

• Chinese: Bilibili through jiangly's account!

Who are you cheering on to win the onsite Semifinals? Here are the teams:

We look forward to your participation!

Hi everyone!

Sponsored by

We are happy to announce that Osijek camp will be returning this Autumn, on August 31-September 8 2024, right before the ICPC World Finals 2024 on 15-20 September 2024 in Astana, Kazakhstan. The camp is hosted by the School of Applied Mathematics and Computer Science of the University of Osijek and is brought to you by the organizing team of adamant and -is-this-fft-.

The camp is inspired by various competitive programming camps that we attended during our active years in ICPC, and is aimed to help college students prepare for ICPC regional contests and finals. The camp will consist of 7 ICPC-style contests and 2 days off.

Details

Participation fee for onsite participants is 150€ per person. It does not include regular meals, travel or accommodation. Some further details about location, travel and food options can be found on the website.

If you want to participate, but are unable to come onsite, we offer a reduced fee of 100€ per person for online participation. It is also possible to reduce fees individually if you are unable to attend some of the contests. This will be handled on a case-by-case basis.

We support and empathize with those affected by the ongoing war in Ukraine, therefore we offer a 100€ discount for affected individuals and teams affiliated with Ukrainian institutions. In other words, the fees would be 50€ and 0€ per person for onsite and online participation correspondingly.

The expected starting time for the contests is 10am CET. For online participants, it is still a preferred starting time, but we will make accommodations for virtual participation at a later time, whe really necessary.

Most of our contests are originally developed for the camp. A small number of contests may be based on previous contests that have not been released to the general public. If you have seen some problems of a contest before, you can't participate on that day. We will privately contact participants who might be affected.

After the camp, we will have a silence period during which camp materials will not be released to the public. We ask participants not to discuss the problems in public unless they obtained an explicit permission from contest authors.

Participants

If you are interested in participating, please fill the form here.

We ask you to register before August 23 if you want to participate online and before August 16 if you want to participate onsite.

Also, if your university or organization has a lively ICPC community that may be interested in attending the camp, and you have some contacts of people in charge (e.g. coaches) we would highly appreciate if you could share some details in a direct message to me (adamant) or Tähvend (-is-this-fft-). Thanks!

Problemsetters

We'd like to thank and praise the authors of the contests in the camp:

• conqueror_of_tourist — ICPC 2022 world finalist. Codeforces LGM in Python.
• tfg — ICPC 2018 and 2019 World Finalist, sqrt decomposition enjoyer and the person that optimized the intended complexity of 1508F - Optimal Encoding.
• Farhod — Codeforces IGM, 2x IOI silver medalist, hates ad hoc problems.
• Amtek — CERC 2022 and 2023 champion. ICPC 2023 and 2024 finalist.
• jacynkaa — CERC 2022 champion. ICPC 2021 and 2023 finalist.
• teapotd — CERC 2019 and 2021 gold medalist. ICPC 2020 and 2022 finalist.
• wuhudsm — Codeforces Master, maintainer of TheForce community, author of over 100 competitive programming problems.
• chromate00 — Problemsetter of 28 tasks on Baekjoon, also known for blogs reinventing the wheel several times.
• ToxicPie9 — ICPC 2021 and 2022 finalist. Authored more geometry than non-geometry problems.
• Mustang98, BigBag, Barichek, Denisov, Valera_Grinenko — ICPC World Finals 2020 bronze medalists, SEERC 2023 champions.
• Kevin114514, yaoxi_std, JCY_, Daniel_lele, ducati, Evier., WaReTle, J.Doe, schrodingerstom — students of Nanjing Foreign Language School.

... And others. We would also like to thank Arpa, two times ICPC World Finalist and former Codeforces Contest Coordinator, for his help with reviewing problem proposals. You can find more details about contest rules and technical setup on the website.

Special thanks

Finally, we say special thanks to

• our sponsors, who make the camp possible;
• ICPC foundation for their help and support;
• Codeforces for guidance and promoting this announcement to the main page;
• eolymp for providing an online judge for the contests;
• School of Applied Mathematics and Computer Science of the University of Osijek for the invaluable help and providing a physical location for the camp.

Hello, Codeforces! We're glad to invite you to take part in Codeforces Round 953 (Div. 2), which will start on Jun/16/2024 12:05 (Moscow time). Note the unusual start time of the round. You will be given 6 problems and 2 hours to solve them.

This round will be rated for participants whose rating is below 2100. Participants with higher rating can participate unofficially.

The problems were authored and prepared by Artyom123, IzhtskiyTimofey, bashkort, TheEvilBird, 127.0.0.1, Tikhon228 and me.

The round is based on All-Russian olympiad in the name of Keldysh.

We would like to thank

• Artyom123 for his high-speed coordination;
• A_G, culver0412, AlexRex0, harsh__h, CSQ31, PMiguelez, dazlersan1, htetgm, oaoaoa_mmm, FynjyBath, Mikhango, Ormlis for testing;
• MikeMirzayanov for creating Codeforces and Polygon.

Score distribution: $$$500 - 750 - 1250 - 1500 - 2000 - 2500$$$

UPD: Editorial