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

Hellowo Codeforcers :3

sum and I are very delighted, ecstatic, enchanted, euphoric, excited, exultant, jubilant, overjoyed, and proud to invite you to participate in Codeforces Round 952 (Div. 4), which will start on Jun/11/2024 17:35 (Moscow time). There will be $$$8$$$ problems, with one split into two subtasks, to be solved in $$$2.5$$$ hours.

As usual, I have to copy and paste the following...

The format of the event will be identical to Div. 3 rounds:

• 5-8 tasks;
• ICPC rules with a penalty of 10 minutes for an incorrect submission;
• 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
• by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).

We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.

Only trusted participants of the fourth 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 fourth 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 1400 or higher in the rating.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), then the round will be rated for you.

We want to express overwhelming gratitude to the following individuals for making the contest possible:

Vladosiya and mesanu for coordinating the contest and reviewing the problems.

Dominater069, omeganot, Phi-001, flamestorm, nskybytskyi, willy108, ScarletS, mark, yuan-shen, vgoofficial, htetgm, buffering, yash_9a3b, haochenkang, ETL, natalina, MatthewC3297, and lcsc0 for testing the round.

MikeMirzayanov for the usual.

We suggest reading all of the problems as we have put mucho effort into all of them. Best of luck, mis amigos!

UPD: Editorial

Hello, Codeforces!

We are pleased to announce Codeforces Global Round 26! Thanks to XTX Markets for supporting the initiative! In 2024, we are holding 4 such rounds. The series results will take into account the best 3 participations out of 4.

On Jun/09/2024 17:35 (Moscow time) we will host Codeforces Global Round 26.

Codeforces Global Round 26 marks the second round in the 2024 series of Codeforces Global Rounds. These rounds are open and rated for everyone.

The prizes for this round are as follows:

• The top 30 participants will receive a t-shirt.
• 20 t-shirts will be randomly distributed among participants ranked between 31 and 500, inclusive.

The prizes for the 4-round series in 2024:

• In each round, the top-100 participants get points according to the table.
• A participant's final score will be the sum of the points they earned in their 3 highest-placing rounds.
• The top 20 participants across the series will receive sweatshirts and placement certificates.

We extend our gratitude to XTX Markets for supporting the global rounds initiative in 2024!

The problems were written and prepared by null_awe, flamestorm, le0n, and buffering.

We would also like to thank:

• Our amazing coordinator TheScrasse for his quick and thorough review.
• Our last-minute Russian translator Alexdat2000.
• Our testers bronze_coder, conqueror_of_tourist, Ra16bit, Flamire, Esomer, PurpleCrayon, Ritwin, awesomeguy856, Tekor, Sugar_fan, htetgm, sum, lunchbox, Ste, liympanda, CSQ31, oursaco, Edlue, eggag32, Tsotne533, serichaoo, Mononoke001, redpanda, janY_, tiagodias, pablopalou, S2speed, cry, Marckess, madlogic for their rigorous feedback.

Round Information:

• Duration: $$$3$$$ hours
• Number of problems: $$$8$$$ problems
• Score distribution:
  $$$500 - 750 - (750 + 1250) - 2500 - 3000 - 3000 - 4000 - 5000$$$

We eagerly anticipate your participation!

UPD: Editorial! https://codeforces.com/blog/entry/130252

UPD2:

Winners!
1. tourist
2. jiangly
3. Benq
4. jqdai0815
5. Nachia

First Solves
A: Benq
B: Thienu
C1: nwn
C2: Benq
D: Be_dos
E: Tom66
F: kiwihadron
G: tourist
H: rainboy

Hello, Codeforces!

I am glad to invite you to participate in Codeforces Round 951 (Div. 2), which will take place at Jun/06/2024 17:35 (Moscow time).

This round will be rated for participants with a rating below 2100. Participants with a higher rating can take part out of competition.

You will be offered 6 problems and 2 hours to solve them! Interactive tasks may occur in the round. Please read this blog to get familiar with this type of problems.

All tasks are authored and prepared by me. However, I'd like to thank Greg908 for discussing ideas about problems and useful feedback!

I would like to thank:

• Artyom123 for his amazing coordination!

• 74TrAkToR for the initial help with this round.

• isaf27 for LGM testing.

• dorijanlendvaj, A_G, Mangooste, andrei_boaca and BucketPotato for red testing.

• ArtAlex, salyg1n, Kihihihi, 127.0.0.1, max0000561, ilyakrasnovv and a.nasretdinov for orange testing.

• Semen07 for purple testing.

• newb_programmer for blue testing.

• A1st for cyan testing.

• ishaandas1 for green testing.

• TimoSvyato and HatakeyamaLeo for grey testing.

• MikeMirzayanov and the entire Codeforces team for creating the wonderful platforms Codeforces and Polygon.

The goal was to create problems interesting to solve. Hope you'll enjoy them all!

Score distribution: $$$500 - 1000 - 1500 - 2000 - 2500 - 3000$$$;

Good luck!

UPD: Congratulations to the winners!

Div. 2:

1. Tanikaze_Amane

2. olmrgcsi

3. PMPuns

4. MegalovaniaJ

5. Sylphrena

Div. 1 + Div 2:

1. turmax

2. jiangly

3. kotatsugame

4. peti1234

5. BurnedChicken

Editorial is out!

Hello! Codeforces Round 950 (Div. 3) will start at Jun/03/2024 17:35 (Moscow time). You will be offered 6-8 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. After open hacks all accepted solutions will be rejudged on successful hacks.

You will be given 6-8 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.

Problems have been created and written by our team: myav, Gornak40, senjougaharin and Vladosiya.

We would like to thank:

1. MikeMirzayanov for help with ideas and Polygon and Codeforces platforms.

2. Be_dos, Dominater069, 74TrAkToR, BucketPotato for red testing.

3. KseniaShk, cry, tolbi, ScarletS, nskybytskyi, sevlll777 for yellow testing.

4. mahdi.hasnat, Phantom_Performer, mainyutin for purple testing.

5. natalina, FBI, Kopite, MADE_IN_HEAVEN, mz1 for blue testing.

6. Romakolesn for cyan testing.

Good luck!

P.S.: We are aware of the error that occurred while updating the ratings for Educational Codeforces Round 166. It will be fixed before this round. UPD: We fixed it!

UPD: Editorial is out!

Hello, Codeforces!

We are glad to invite you to participate in Codeforces Round 949 (Div. 2), which will start on May/31/2024 13:05 (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 sinsop90, yinhee and me.

I would like to thank:

• 244mhq for his wonderful coordination.
• sinsop90 and yinhee for providing problem ideas and discussing the problems with me.
• AFewSuns and crazy_sea for providing a better solution to one of the problems.
• Um_nik for the only LGM testing.
• A_G, antontrygubO_o, StarSilk, CharlieV, rui_er and Andreasyan for red testing.
• FengLing, YuJiahe, CSQ31, small_peter and JWRuixi for orange testing.
• yinhee, QwQwf, lovely-ckj, wsc2008qwq and Jryno1 for purple testing.
• sinsop90, dieselhuang, Edwin__VanCleef, wtc, WRuperD, starrykiller and gdf_yhm for blue testing.
• Ender32k and liangbowen for cyan testing.
• ishaandas1 for the only green testing.
• cyz2010 and cppcppcpp3 for grey testing.
• MikeMirzayanov for the great Codeforces and Polygon platforms.
• Last but not the least,

  You

  , for participating!

Scoring distribution: $$$500 - 1000 - 1500 - 2000 - 2500 - 3500$$$.

Good luck & Have fun!

UPD: Congratulations to the winners!

Div 2:

1. cyb0101
2. Feduk_Pro_Spb
3. whale_0086
4. graphcity
5. grass8cos

Div. 1 + Div. 2:

1. maspy
2. Savior-of-Cross
3. Rubikun
4. femboy-wannabe
5. turmax

Editorial and also Simplified Chinese Editorial are out.

Hello Codeforces!

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

On May/30/2024 17:35 (Moscow time) Educational Codeforces Round 166 (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 everyone, we are happy to announce that the 3rd Universal Cup has started officially. Universal Cup is an organization dedicated to offering training resources for competitive programming teams. In the previous season, over 900 teams from more than 500 affiliations all over the world, registered and participated in a total of 28 stages, encompassing contests from Asia, Europe, and America. We also want to express our gratitude to our sponsor Huawei.

- Semifinal and Summer Summit

As announced before (Link), we will host the 2nd Universal Cup Semifinal on June 23, 2024. The contest will start at 17:00 (UTC +8) and end at 22:00 (UTC +8).

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 UCup Finals, sponsored by Huawei, we also prepare 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 when processing):

After the online semifinal, we will host a stream of all invited teams competing in the semifinal contest at the Summer Summit event in Cancun, along with problem analysis. The stream will start at 22:00 (UTC +8) and end at 03:00 (UTC +8).

• English: YouTube (through tourist's account!)

• Chinese: Bilibili (through jiangly's account!)

Here is a list of teams that will be competing onsite:

We also prepare prizes for this onsite competition:

- 3rd Season Online Stage

As usual, this season's main activity is our online stage, where we hold weekly mirror contests. Please refer to our website https://ucup.ac/ for previous results. If you are interested in participation, please register following the instructions on Registration.

The online stage rule is still the same as last season:

- 08:00 (UTC +8) on Saturday ~ 13:00 (UTC +8) on Saturday
- 10:00 (UTC +8) on Saturday ~ 15:00 (UTC +8) on Saturday
- 13:00 (UTC +8) on Saturday ~ 18:00 (UTC +8) on Saturday
- 16:00 (UTC +8) on Saturday ~ 21:00 (UTC +8) on Saturday
- 19:00 (UTC +8) on Saturday ~ 24:00 (UTC +8) on Saturday
- 21:00 (UTC +8) on Saturday ~ 02:00 (UTC +8) on Sunday
- 23:00 (UTC +8) on Saturday ~ 04:00 (UTC +8) on Sunday
- 02:00 (UTC +8) on Sunday ~ 07:00 (UTC +8) on Sunday

To provide more convenience, we implement a few more features on the system, including team composition, extra time window application, etc:

Lastly, we would like to express our gratitude to MikeMirzayanov for letting us advertise Universal Cup in Codeforces and providing the great platform Codeforces and Polygon to help prepare contests. We are also very thankful to all contest stage setters for your support of the Universal Cup. If any setter would like to propose a stage, please feel free to contact us.

Universal Cup Committee:

• Jingbang chenjb Chen
• Yuhao jqdai0815 Du
• Lingyu jiangly Jiang
• Yaowei Sugar_fan Lyu
• Qingyu Qingyu Shi
• Yaohui quailty Zeng

Hello everyone!

We, the RGBTeam (qwerty787788, Romka and tourist), are huge fans of heuristic programming competitions and are quite saddened by the fact that they are becoming less and less frequent each year. One day, we decided to organize our own competition :) Despite the fact that such ideas often remain just ideas, this time we have a serious mindset, and now we want to invite you all to participate in the first — and hopefully not last — Code Weekend #1!

The competition will be held in a format quite similar to ICFPC/Google Hashcode — there will be one problem and several dozen tests for it. You will need to submit just an output according to the rules of the problem for each test, which can be obtained using any algorithms, written in any language, and running for any duration of time. Midway through the competition, the problem statement will be expanded, and new tests will be added.

The competition starts on June 7th at 21:00 UTC and will last 48 hours. A day after it begins, on June 8th at 21:00 UTC, a second, expanded version of the problem along with a set of tests for it will be released. The competition ends another day after the release of the second version, on June 9th at 21:00 UTC.

The expanded version of the problem will be a superset of the basic version. For instance, if the problem is "given a chess position, find the best move," the basic version may only include pawns, bishops, and knights, while the expanded version will use rooks and queens.

The competition is team-based, and there is no limit on team size, but we've tried to balance the problem in a way that larger teams don't have a significant advantage over smaller ones. Therefore, the recommended team size is 1-4 people.

Unlike ICFPC, the focus of the competition will be on heuristic algorithms rather than functional programming (although in recent years ICFPC hasn't been focused on FP either).

Attention! The contest will be held on the website https://codeweekend.dev, you need to register there (once per team). All the announcements during the competition will be in the Discord chat, so join it via the link https://discord.gg/M6pG5zp3DF. Be sure to invite your friends, relatives, pets, and anyone else who might find it interesting :)

UPD. Our competition will be generously sponsored by the TON Foundation, for which we are immensely grateful!

As a result, the following prizes will be awarded in the competition:

• 1st place — 400 TON
• 2nd place — 300 TON
• 3rd place — 200 TON
• 4th place — 100 TON

Additional prizes:

• 1st place after the first day of the competition — 111 TON.
• At the end of each minute of the competition, the current leader (provided there is at least one team with a positive score) receives 0.1 TON.
• 300 TON will be distributed equally for the best solution of each test at the end of the competition. For example, if there are 10 tests, and Team A has the best result in the first three tests while Team B has the best result in the remaining seven, Team A will receive 300/10*3 = 90 TON, and Team B will receive 300/10*7 = 210 TON.

All ties are resolved by time — the team that achieves its result earlier ranks higher.

Thus, the total prize fund for the competition is over $10,000 at the current exchange rate.

Hello, Codeforces!

After a year of anticipation and several complete changes to the problem set, we are glad to invite you to take part in Codeforces Round 948 (Div. 2), which will start on Sunday, May/26/2024 17:35 (Moscow time). This round will be rated for participants whose rating is below 2100. Participants with higher ratings may participate out of the competition.

You will be given 5 problems and 2 hours to solve them. All the problems in the round are created and prepared by Stefan2417 and alexchist.

The round may include one or more interactive problems. Please read this blog to get familiar with this type of problems.

We would like to thank:

• Vladithur for excellent round coordination!

• A_G, JustNik77, AgafonovArtem, MADKIRUS, AndreyPavlov, PBBx0, Alexdat2000, RP-1, mwen, MrDelrus, tiom4eg, ezraft, TheEvilBird, Codula, Vamperox for testing the round and providing valuable feedback.

• MikeMirzayanov, geranazavr555, geranazavr555, vbandurin, ChurakovaAlexandra, medvezhonokok, Vladosiya and KAN for maintaining and developing the Codeforces and Polygon platforms!

Score distribution: $$$500 — 1250 — 1750 — 2000 — 2500$$$.

Your perception of the scoring may vary, so be sure to read the later problems if you get stuck on one.

Upd: Congratulations to the Winners!

Div 2:

1. sun_gan_chou_yu_guan

2. Maksiwelle

3. suomynonA

4. new_mistakes

5. Kosyaaa

Div 1+2:

1. tourist

2. Sugar_fan

3. sun_gan_chou_yu_guan

4. abc864197532

5. BurnedChicken

Upd: editorial