Hello Codeforces!

$$$\newline$$$

It's been a while, today GlowCheese and I are delighted to invite you to participate in Codeforces Round 963 (Div. 2). This round will be rated for all participants with a rating lower than 2100.

Our round will start on Aug/04/2024 17:35 (Moscow time). You will be given 6 problems and 120 minutes to solve them.

This contest is brought to you by Code Mely, a Vietnamese community for Computer Science. Reach out to us here.

Special thanks to:

• Akulyat for his wonderful coordination and translating our statements.
• Our testers: Umi, lmqzzz, danghuyhau, _Fake4Fun, AkiLotus, LetterC67, McPqndq, Evirir, Lyde, Hihihah, Yugi.Hacker, hhoangcp, t1r3d_, mp1309, phungthienphuoc, Etohari, aeonary_will_win_VOI25, hydroshiba, zeena., bibimoni, kodomo_tachi, StenSoSmol, Habaxl, and DOCUTEE.
• DeMen100ns, shine_, Asamai, Miko_UwU and nohandle_5 for joining with us.
• MikeMirzayanov for amazing platforms Codeforces and Polygon.
• KFC for their chicken nuggets.
• You for participating. $$$\newline$$$

Score distribution: $$$500 - 1000 - 1500 - 2000 - 2750 - (2500 - 1000)$$$

Hope to see you in the final standings!

UPD1. Editorial is out!

UPD2. Congratulations to the winners:

Div.2:

1. kkkksc03
2. imwh
3. _acsm_
4. _wrpwrp
5. rainboy

Div.1 + Div.2:

1. A_G
2. arvindf232
3. Rubikun
4. kkkksc03
5. Sugar_fan

Hi!

Today I was shown a tweet https://x.com/deedydas/status/1818477947277525242

I'll quote the text here:

International Olympiad winners often go on to start world-changing things. OpenAI, Two Sigma, Telegram, Databricks, Perplexity, Devin, Ethereum, Udemy and even Python! You'll recognize some heavy hitters on the list. Nikolai Durov may be the most decorated of then all.

And there's also an interesting table there (I see Codeforcers there!):

Codeforces will soon turn 15 years old. Maybe this is an occasion to try to compile such a list? Suggest candidates in the comments! Please include at least three fields about the person: Handle, Name, and Career.

Hello Codeforces!

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

On Jul/30/2024 17:35 (Moscow time) Educational Codeforces Round 168 (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 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!

We are pleased to invite you to Pinely Round 4 (Div. 1 + Div. 2), which will start on Jul/28/2024 17:35 (Moscow time). The round will be rated for everyone.

You will be given 9 problems and 3 hours to solve them. There is at least one interactive problem, so please read the guide for interactive problems if you are unfamiliar with it.

The problems were authored and prepared by me.

We would like to thank:

• errorgorn for the excellent coordination.
• dXqwq, StarSilk, jiangbowen_, Endagorion, JCY_, jiangbowen, QwertyPi, chen_zexing, YocyCraft, zeliboba, HackerMonk, axs7384, Vladithur, davi_bart, prvocislo, leinad2, Andyvanh1, stasio6, hychyc, bitset, bonopo, Mucosolvan, RandomLB, CSQ31, Myrcella, NamelessOIer, guapisolo, Enigmurl, satyam343, Vingying0, qinyuzhou, 7oSkaaa, Geisel.Library, EpicChadGamer, AXXWTGST, and pengrui for testing the round and providing valuable feedback.
• Alexdat2000 for translating the statements to Russian.
• MikeMirzayanov for the great Codeforces and Polygon platform.

We hope you will enjoy the round!

Score distribution: $$$250 - 500 - 1000 - 1500 - 2000 - 2500 - 3000 - 3500 - 4000$$$

The editorial is here.

Congratulations to the winners!

1. tourist
2. jqdai0815
3. Radewoosh
4. ksun48
5. Rewinding
6. hos.lyric
7. jiangly
8. Benq
9. BurnedChicken
10. Szoboszlai10

This round is made possible with the support of Pinely!

Pinely is a dynamic algorithmic trading firm with a presence in Singapore, the Netherlands, and Cyprus. We specialize in high-frequency and ultra-low latency trading. Our team of mathematicians, programmers, engineers, and computer scientists tackles everyday challenges like developing trading strategies, optimizing systems for minimal latency, saving and processing large volumes of historical data.

Working at Pinely demands exceptional C++ coding, algorithmic thinking, and mathematical intuition, attracting top talent, including winners and awardees of such competitions as ICPC, IMC, HITB PRO CTF, Google HashCode, etc.

Learn more about us on our website or find our employees on CF. To join our team, please send your CV to [email protected], even if you are not participating in the contest.

Prizes: The top 30 contestants will receive a branded plush pine tree!

Hewwo Cowodeforcers!

sum and I are overjoyed to welcome you to participate in Codeforces Round 962 (Div. 3) on Jul/26/2024 17:35 (Moscow time). This contest is the last stop on our mission to problemset for every division. We hope you've been enjoying our stuff so far!

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 7 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for each 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.

We would like to orz the following individuals for making the contest possible:

• Vladosiya for the quality coordination.

• Benq and satyam343 for overseeing the creation of this contest.

• Yam, omeganot, tyr0Whiz, awesomeguy856, 18o3, Sokol080808, Phi-001, milind0110, NovusStellachan, vgoofficial, carnation13, SashaT9, Pa_sha, Qualified, Prady, ntarsis30, waidenf, Non-origination, Orange905, AceKnight7, ETL for testing the contest and providing valuable feedback.

Thank you for reading and we hope you have a fun and educational interstellar adventure :3

UPD: Editorial

Attention! Attention! Attention! Don't miss this opportunity!

Codeforces Round 961 (Div. 2) will be held on Jul/23/2024 17:35 (Moscow time)!

Problems for this round were prepared by a team of Neapolis University Pafos (yes, you've seen its logo in Educational Round announcements) students: Vitaly503, goncharovmike, ikrpprppp.

You will be given 5 problems some of which will be divided into two subtasks and 2 hours to solve them.

Important disclaimer! Some problems of this round were also used in CPFED x JetBrains Training Camp 2024. NUP Contest in Kazakhstan this June. If you've participated in this camp or seen the problems from there, please do not participate in this round.

We would like to thank:

• Akulyat for coordinating the round and frequent pinging;

• pashka for valuable discussions and the idea of one of the problems;

• MikeMirzayanov for the all-powerful Codeforces and Polygon platforms;

• Our testers denk, artem3605, physics0523, BurnedChicken, oursaco, AdityaTakkar, shade34, md_nihal, Vamperox, Binary_Thinker, Dominater069, -2.71, Yugandhar_Master, Banis, dazlersan1, MaxLevitsky, larush, aufannn, thenymphsofdelphi, turmax, ishaandas1, vahtang, GrandFruit, okwedook, Vladithur;

• Participants of the onsite version of this contest in Kazakhstan who also made this round better: AmirMakaM, kaztayev, MnTm, shenfe1, mispertion20, dondurma, N29, Relice, k1ngash, Alihan_8, Otalp, Tima19, kanye_east, adiyer, BallBreaker, I_Love_Diar_Narumov, Tangirkul, Issa, fft97, Aiperiii, Bichpaket, Baytoro, kylych03, Wansur, Chalishkan;

• And participants of the Codeforces Round 961 (Div. 2) (i.e. you)!

Not-so-important not-so-disclaimer. If you're interested in getting a Bachelor's degree in computer science in the indefinite future, you might want to take a look at Computer Science and Artificial Intelligence program in our university administered by JetBrains.

UPD. Scoring distribution: $$$500 + (1000+500) + 1750 + 2250 + (2500 + 1500)$$$

UPD2. Congratulations to the winners:

Div 2:

1. rainboy

2. GidrAcH

3. toma_ariciu

4. biximo

5. zhengjc

Div 1 + Div 2:

1. tourist

2. Ormlis

3. potato167

4. risujiroh

5. kotatsugame

UPD3. Editorial.

Hello Codeforces!

I have the pleasure of inviting you to participate in Codeforces Round 960 (Div. 2), which will start on Jul/20/2024 17:35 (Moscow time).

The problems were prepared and authored by wuhudsm.

You will be given 6 problems and 2 hours to solve, one of the problems is divided into two subtasks.

One of the problems may be interactive. So, please refer to the guide on interactive problems if you are unfamiliar with them.

I would like to thank:

• Akulyat for coordinating the round;
• BurnedChicken for the only LGM testing;
• physics0523, liympanda, culver0412, Dominater069, TheScrasse, Andreasyan,satyam343 for GM and IGM testing;
• Error_Yuan, IanISam, Little_Sheep_Yawn, NemanjaSo2005, aufannn, IceKnight1093, and pavlekn for M and IM testing;
• Muhammad-Saram, vikram108, PROELECTRO444, htetgm, n0sk1ll, and AkibAzmain for CM testing;
• kHarsh3715, beyondpluto, larush, AdityaTakkar, Banis,Abhishek_Srivastava, Yugandhar_Master, chromate00, and astilate for Expert testing;
• md_nihal, HexShift, and dazlersan1 for Specialist testing;
• yash_04, and ishaandas1 for the Pupil testing;
• -2.71, and Binary_Thinker for the Newbie testing;
• tibinyte for the Illegal newbie lying face testing;
• MikeMirzayanov for the great Codeforces and Polygon platforms;
• CHATGPT for solving $$$0$$$ problems : ) ;
• And at last but not least, You for participating in the round!

Good luck and have fun!

Score distribution: $$$500 - 1000 - 1500 - 1750 - (2000+750) - 3000$$$

UPD:

Editorial

Congrats for the winners!

Div 2:

1. 0101byc

2. Psychotic_D

3. roIandpetrean

4. skahl15

5. thawin.ice

Div 1+Div 2:

1. tourist

2. jiangly

3. noimi

4. Sugar_fan

5. 0101byc

Hello, Codeforces!

I am pleased to invite you to participate in Codeforces Round 959 sponsored by NEAR (Div. 1 + Div. 2), which will be held at Jul/18/2024 17:35 (Moscow time). You will be given 8 problems and 2 hours to solve them. It will be rated for all participants.

The theme of the round is computer games!

Tasks for the round were prepared by EJIC_B_KEDAX, zwezdinv, green_gold_dog, molney, azureglow and Sokol080808.

We would like to thank everyone who assisted in the preparation of this round:

1. Our coordinator 74TrAkToR for his useful advices and help in preparing the tasks!

2. Qwerty1232 for red interest in testing the round.

3. turmax for the red-black testing.

4. makrav, arbuzick, Anonymous_Noob, Hyperbolic for red testing.

5. ivan.alexeev, alenenok, Kihihihi, azureglow, pakhomovee, plagues, IzhtskiyTimofey, FelixArg, XaRDKoDblCH, meowcneil, AndreyPavlov, djm03178, MylnikovNikolay for yellow testing.

6. Mr_Ell, krigare, marzipan, TimVen74, coder8080, MichsSS, PieArmy, tvladm, Vladosiya, bashem for purple testing.

7. Algolagon, PoDuReMaN, zarubin, IgorA, leoper, kovir_aleksey_korroy, Kosya, Vamperox for blue testing.

8. MakGeoKar, viteli for cyan testing.

9. Sonya_2009, ishaandas1 for green testing.

10. MikeMirzayanov for the excellent Codeforces and Polygon systems.

I also congratulate green_gold_dog on his birthday and wish him good luck on IOI.

This round is supported by NEAR!

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 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. You can join the system following this: https://codeforces.net/settings/near-connect-account

Thanks to NEAR for providing the following prizes to the contestants:

• 1st place: 512 Ⓝ;
• 2nd and 3rd places: 256 Ⓝ each;
• 4th to 7th places: 128 Ⓝ each;
• and so on;
• 512th to 1023th places: 1 Ⓝ each.

Score distribution: $$$500-1000-1250-2000-2000-2500-2750-3750$$$

Good luck!

UPD: Editorial

UPD2: Congratulations for the winners:

1. tourist

2. ecnerwala

3. orzdevinwang

4. Egor

5. jiangly

Hi.

In Spring semester, I conducted a short course titled “Dynamic Programming” in SPbSU. To complete the course, the students solved many training problems, and also prepared their own problem in Polygon.

For the majority of the students, it was the first problem they authored. Nevertheless, the result looks cute. A couple problems went to local contests. From the remaining ones, I composed two trainings and put them on Codeforces. The trainings are set at the following time:

• first: Dynamic Programming, SPbSU 2024, Training 1, starts on Jul/06/2024 11:30 (Moscow time), duration: 3 hours (statements, results, tutorial)
• second: Dynamic Programming, SPbSU 2024, Training 2, starts on Jul/07/2024 11:30 (Moscow time), duration: 3 hours (statements, results, tutorial)

Each training contains both easy and hard problems. The majority of the problems are intended for training. I think orange participants and below will have enough problems for the duration. The problems go in randomized order.

Good luck!

Hello Codeforces!

I am glad to invite you to Codeforces Round 958 (Div. 2) which will start on Jul/15/2024 17:35 (Moscow time).

The contest will last for 2 hours with 6 tasks for you to solve. The contest will only be rated for those with a rating not higher than 2099, but high-rated competitive programmers are also more than welcome to participate out of competition.

The score distribution is: 500-1000-1000-2000-2500-3500

The contest will be impossible without the help from:

• 244mhq for wonderful coordination.
• gyh20, Dominater069, Um_nik, A_G, omeganot, tkl2006, harsh__h, oursaco, Hori, kostia244, ishaandas1, maomao90, waidenf, Stefan2417, MisterReaper for testing.
• MikeMirzayanov for Codeforces and Polygon.

Good luck and have fun!

Update: editorial

Update: video editorial