Hello again!

VK Cup 2021 - Final (Engine) starts very soon: on Aug/22/2021 15:05 (Moscow time). Today, 32 best contestants of the elimination round will be fighting for cash prizes and eternal glory.

You can follow the course of the contest and root for your favorite contestants via this link.

Everyone except for VK Cup 2021 finalists is invited to Codeforces Round #740 (Div. 1, based on VK Cup 2021 - Final (Engine)) and Codeforces Round #740 (Div. 2, based on VK Cup 2021 - Final (Engine)) that start a couple of days later: on Aug/24/2021 17:35 (Moscow time). The rounds will be rated for everyone.

All the problems were authored and prepared by me. Big thanks to everyone without whom this round would not be possible: KAN, PavelKunyavskiy, scott_wu, xiaowuc1, 1-gon, Aleks5d, lperovskaya, MikeMirzayanov. Special thanks to s-quark (2nd place of the first ever VK Cup 2012!) for inspiring problem titles.

You will be given 6 problems and 2 hours 30 minutes to solve them in both divisions. It is recommended to read all the problems. Good luck!

UPD: Scoring distribution in the VK Cup finals: 500 — 1250 — 1500 — 2000 — 3000 — 3500

UPD2: Congratulations to the winners of the VK Cup 2021 Final Round!

1. never_giveup
2. Maksim1744
3. Um_nik
4. SpyCheese
5. Nebuchadnezzar
6. vepifanov
7. Golovanov399

UPD3: Division 1 round will be held on the VK Cup 2021 Finals problem set without any changes.

Scoring distribution for Div. 1: 500 — 1250 — 1500 — 2000 — 3000 — 3500

In Division 2 problems BDEF will match problems ABCD of Div. 1. Problems A and C of Div. 2 will be similar to problems F and E of Div. 1 (albeit being much easier). Besides that, problem D of Div. 2 will have a subtask with lower constraints than the original problem.

Scoring distribution for Div. 2: 500 — 1250 — 1250 — (1500 + 1000) — 2500 — 3500

As a reminder, the standings of the VK Cup Finals are available via this link — feel free to try gaining an advantage using all the information available before the round :)

UPD4: Editorial is available.

Hello, Codeforces.

I and DK318 joined the Codeforces team in June. These three months we mainly dealt with the development of the Polygon platform. In this post, we would like to present to you a list of what we have done during this time. Most of the changes were made to attain easier problem creation. This list does not include minor bug fixes or any improvements that are invisible to users.

Tables support when rendering statements in HTML

Now it's possible to insert the most basic tables in your HTML statements. For example, you can show the scoring system of your problem or insert several images side by side. Only column text alignment and border specification are supported now.

A brief manual for writing statements

We bet a lot of users who wrote statements were confused by the fact that a lot of TeX commands are not working when rendering in HTML. Now you can access the manual on the statements page to learn about supported commands with examples as well as other tips for writing better statements.

You can check out the manual here.

Reworked how one can add problems into a contest

We completely reworked the way you add problems on the contest page. You can select the problems from the list of accessible problems: they will be added to a separate list. You can also filter your problems so you can find the needed one much quicker. We performed some optimizations as well so even if you have thousands of accessible problems, this page will lag much less.

Hello, Codeforces!

I'm glad to invite you to amazing (we've tried to make it such) Codeforces Round #739 (Div. 3) which will start on Aug/18/2021 17:35 (Moscow time). This round is my (MrPaul_TUser) second round a significant contribution to which was also made by MikeMirzayanov, BledDest, DK318, unreal.eugene, and geranazavr555.

The round contains 7-8 problems. The difficulties of the problems are expected 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 1600 or higher, can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round, it will be a 12-hour phase of open hacks. We tried to make really strong tests — just like you will be surprised if many solutions fail after the contest is over.

You will be given 7-8 problems and 2 hours 15 minutes to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) 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 trusted participants of the third division, you must:

• take part in at least two 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.

Thanks to powergee101, artsin666, WitchOfTruth, ivanzuki, A_Killer, mahade31, I_Remember_Olya_ashmelev, nooinenoojno, Gassa, _c_k_r_, spotless, iankury, UpS0lver, ncduy0303, and Vladosiya for testing the round and improving tasks.

Good luck and have fun!

UPD Editorial

Hi Codeforces!

We are glad to invite you to our first Codeforces Round Codeforces Round #738 (Div. 2) which will be held on Aug/15/2021 17:35 (Moscow time). This round will be rated for participants with rating less than 2100. We will be glad to see participants from the first division to join out of competition as well!

In this round, as the best friend of Mocha's, you are going to help her to solve the problems she meets.

The problems are prepared by 2sozx, JJLeo, Serval, CalvinJin and me. We hope you will enjoy the round. :P

We would like to thank:

• 1-gon for awesome coordination of this round and helping us improve our problems.

• Toxel for excellent testing and discussion of this round.

• cppascalinux, PurpleCrayon, ijxjdjd, m371, qxforever, fixed_lxy, HKvv, jxm2001, GGN_2015, I-AK-ACM, wzy2001wzy, xrbxbn, BH18376359, zhtjtcz, lgwza, qwertyczx, godel_bach, withinlover, Saisyc, Matrix53, rancy, asrinivasan007, QuangBuiYT, lcj_rating1600, Atlantis592, shakugan_no_shanatan_, DovahkiinGA and 5095187020216 for testing our rounds

• MikeMirzayanov for the amazing Codeforces and Polygon platforms.

You will be given 5 problems to solve in 2 hours.

Scoring distribution: 500—750—1000—(1500—1500)—3000.

We recommend you to read the statements of all problems. Good luck & Have fun! :D

UPD: Great thanks to KAN and isaf27 for helping with Russian language translation and clarifications.

UPD2: Sorry for the long queue and my mistake in estimating the difficulty of problem D2 and E.

UPD3: Editorial is available now.

UPD4: Thank you for your participation in this round! Congratulations to the winners!

Div. 2

1. Suckmycode
2. Wlxsohandsome
3. idontwannawin
4. shu_ya_zi
5. _Kubic_

Div. 1 + Div. 2

1. neal
2. ksun48
3. Geothermal
4. sjc061031
5. Kirill22

Hello, Codeforces!

I'm glad to invite you to Codeforces Round #737 (Div. 2) , which will be held on Monday, August 9, 2021 at 16:35 UTC+2.

This round rated for the participants with rating lower than 2100.

You will be given 5 problems and 2 hours to solve them.all problems were prepared by me and AhmedEzzatG.

One of the problems will be interactive. So, it is recommended to read the guide on interactive problems before the round.

I would like to thank -

1. Aleks5d, for awesome coordination of our round and suggested one of the problems.

2. Kaneki-kun for help us to prepare the problems. compiler_101 ,Shanks ,DeadPillow , and Omar_Elawady for discussing and testing the problems.

3. MikeMirzayanov, for the amazing Codeforces and Polygon platforms.

4. Testers physics0523 , BlueDiamond , Tlatoani ,mahmoudbadawy , Andreasyan , IsaacMoris , Error_404 , Basilhijaz , hu_tao , m371 , Blobo2_Blobo2 , elizkaveta , zetamoo , Mohammed_Atef_Hassan , tdpencil , mcdx9524 , nGu , _Hosam , Bakry_ , N4553R , rkm62 , Hemose , Uzumaki_Narutoo , and our VIP tester 1-gon.

The statements are short and I have tried to make the pretests strong. I encourage you to read all the problems.

This is our first official round on Codeforces. We are sincerely looking forward to your participation. We hope everyone will enjoy it.

Good luck and see you in the standings!

UPD1: I want to thank Aleks5d for translating statements into Russian and mouse_wireless author of one of tasks.

UPD2: Scoring distribution: 500 — 1000 — 1750 — 2500 — 3000

UPD3: Editorial

UPD4:

Winners

Congratulations to all our winners in the round!

Div.1 + Div.2:

1. tourist

2. jiangly

3. m_99

4. BigBag

5. Geothermal

Div2:

1. treborr

2. juruo_cjl

3. RGB_ICPC4

4. zxcgod

5. Hanabi2333

Hello, Westeros!

I'm glad to invite you to Codeforces Round #736 (Div. 1) and Codeforces Round #736 (Div. 2), which will be held on Aug/01/2021 17:35 (Moscow time).

The round will be rated for both divisions. Each division will have 5-7 problems and 2 hours and 15 minutes to solve them. There will not be an interactive problem, so yay!!!

This round would not have been possible without the following individuals:

1. Aleks5d, for awesome coordination of my round.
2. Benq, for extensive testing and contributions throughout the round, especially for 1548E - Gregor and the Two Painters.
3. 1-gon, for discussing problems and statements with me for hours on Discord.
4. amgfrthsp, for translating statements into Russian.
5. MikeMirzayanov, for Codeforces and Polygon.

32 testers

The round had a total of 32 testers. I tried to get a "rainbow" of testers to help guarantee a most balanced round. Thank to you to each and every one of them!

• Benq, hos.lyric, ecnerwala, Um_nik
• TadijaSebez, 1-gon, galen_colin, Tlatoani, dorijanlendvaj, rqi
• emorgan5289, TheOneYouWant
• penguinhacker, 221, AquaMoon
• ajpiano, arvindr9, ijxjdjd
• m371, nnv-nick, alexwice, gupta_samarth
• LostCoder16, 4qqqq, gerzytet, growup974, NemanjaSo2005
• RobinPH, zyzzsama, I_Love_YrNameCouldBeHere
• QuangBuiYT
• tdpencil

This is my first round ever written, and I sincerely hope you enjoy it, regardless of your rating!

Score Distribution

Div 1: 500 — 1000 — 1750 — (2000 — 1000) — 3500

Div 2: 500 — 750 — 1250 — 2000 — 2500 — (2000 — 1500)

UPD: Editorial

Winners

Congratulations to all our winners in the round!

Div1

1. Miracle03, congratulations on the AK!
2. tourist, congratulations on the AK!
3. yhx-12243
4. heno239
5. Isonan

Special congratulations to antontrygubO_o and Subconscious for definitely reaching the rank of Legendary Grandmaster!

Div2

1. dingdingsb
2. pAFOstd
3. black_trees
4. lajixtc
5. soumilaggarwal

Fastest Solves

• 1549A - Gregor and Cryptography: robivirt at 53 seconds!
• 1549B - Gregor and the Pawn Game: speedforces at 4 minutes!
• 1548A - Web of Lies: tourist at 3 minutes!
• 1548B - Integers Have Friends: tourist at 7 minutes!
• 1548C - The Three Little Pigs: gisp_zjz at 19 minutes!
• 1548D1 - Gregor and the Odd Cows (Easy): tourist at 20 minutes!
• 1548D2 - Gregor and the Odd Cows (Hard): tourist at 65 minutes!
• 1548E - Gregor and the Two Painters: mango_lassi at 80 minutes!

Hello Codeforces!

On Jul/30/2021 17:35 (Moscow time) Educational Codeforces Round 112 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

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, Vladimir vovuh Petrov, 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!

Our friends at Harbour.Space also have a message for you:

Hello once again, Codeforces!

It’s been a week since we completed our Harbour.Space Scholarship Contest. It’s was an intense journey, but we are excited to share the results of the contest and take this time to give a word of appreciation to every participant.

One more big shout out to the authors and round coordinator who made this contest happen in a short period of time:

• Round Coordinator: BledDest
• Authors: kefaa2, bthero, Adel_SaadEddin, Zaher, Errichto, marX.

Thank you again for all your hard work.

Congratulations to all the winners and runner-ups who got the opportunity to go through the admissions process and who are eligible for a full scholarship.

1st-3rd Places: Ali.Kh, Yousef_Salama, Krauze

4th-10th Places: sunyx, 777, Redhood, Meijer, Gioto, kpw29, Huah2

11th-15th Places: dhruvsomani, adamant, Kaitokid, khiro, c8kbf

We are pleased to announce that we have reviewed all the winners and will make a final decision about additional scholarships soon. Stay tuned and keep an eye on your inbox!

Remember, to claim the scholarship you need to respond to the email sent 3-4 days ago. And just to make sure email addresses weren’t misspelt, we want to take this opportunity and ask Yousef_Salama, Huah2, adamant, c8kbf, Naseem17 to contact us via email (almaz.aubakirov@harbour.space) or directly on Codeforces platform (Harbour.Space)

Congratulations to the winners:

57 successful hacks and 612 unsuccessful hacks were made in total!

And finally people who were the first to solve each problem:

UPD: Editorial is out

কি অবস্থা মামা? (That's Bengali for "What's up dude?")

I am super excited to invite you to participate in Codeforces Round #735 (Div. 2) which will be held on Jul/29/2021 17:35 (Moscow time). This round is rated for future LGM participants whose current rating is $$$\le 2099$$$.

You will be given $$$5$$$ problems and $$$2$$$ hours to solve them. All the problems are authored and prepared by me.

I would like to thank -

• antontrygubO_o for his awe-inspiring coordination of the round and rejecting my problems, and thus hurting my feelings.
• Um_nik, _Ash__, Anachor, Arg_007, Alpha_Q, DAleksa, steinum, Tasdid, border, mk_Shahriar, t17, imAnik, Alfeh, Aritra741, FrozenBlood, SajidZakaria, ovis96, _________, Raiden, YoyOyoYOy000y000 and tdpencil for testing the round. They were excellent testers, so they deserve the upvotes that they will be begging for in the comments.
• The great MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• You, for existing and participating in the round. Also, thanks for giving your best to try to achieve everything you set out to do. You will eventually be happy. Just hold right there.

The statements are super short and I have tried to make the pretests strong. I encourage you to read all the problems and solve them all.

I would like to dedicate this contest to the fallen king, my father, who died two months ago. May he and all the departed good souls rest in peace.

Scoring distribution: $$$750 - 1250 - 1750 - 2000 - 3000$$$.

Good Luck!

UPD1: Thanks for participating, I hope that you guys loved the problems, and sorry for B being a bit difficult than usual.

UPD2: Editorial

UPD3: Congratulations to the winners.

Div.1 + Div.2:

1. turmax
2. Karry5307_AK_NOI2021
3. SSRS_
4. Pyqe
5. X_qaeq

Div.2:

1. Karry5307_AK_NOI2021
2. X_qaeq
3. MiFaFaMYY
4. sbren_sbeve
5. LilliaAsupurei

Also, congratulations to the first solvers:

A: LiM_256, at $$$0$$$ mins!
B: RinShima, at $$$4$$$ mins!
C: xiaofan7, at $$$7$$$ mins!
D: 6945930042DucLA, at $$$7$$$ mins!
E: rainboy, at $$$23$$$ mins!

Hi!

On Jul/25/2021 17:35 (Moscow time) we will host Codeforces Global Round 15.

This is the third round of the 2021 series of Codeforces Global Rounds. The rounds are open and rated for everybody.

The prizes for this round are as follows:

• 30 best participants get a t-shirt.
• 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.

The prizes for the 6-round series in 2021:

• In each round top-100 participants get points according to the table.
• The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
• The best 20 participants over all series get sweatshirts and place certificates.

Thanks to XTX, which in 2021 supported the global rounds initiative!

Problems for this round are set by cip999 and me. Thanks a lot to the coordinator antontrygubO_o, to the testers gamegame, ajit, golions, skydogli, McDic, rabaiBomkarBittalBang, nweeks, Marckess, HenriqueBrito, gratus907, bWayne, zscoder, TheOneYouWant, and to MikeMirzayanov for the Codeforces and Polygon platforms.

You will be given 9 problems and 2 hours 45 minutes to solve them.

The scoring distribution is 250-500-1000-1000-1500-1500-2500-2750-3750.

Good luck and see you in the standings!

UPDATE 1: Thank you very much for participating, we hope you liked the problems (and sorry to top contestants for giving a not-so-fresh problem I).

Here you can find the editorial (with a bit of behind-the-scenes, some obscenely wrong preditions, and hints for all the problems).

UPDATE 2: Congratulations to the winners!

1. tourist
2. ksun48
3. Benq
4. Petr
5. peehs_moorhsum
6. TadijaSebez
7. sunset
8. Um_nik
9. ko_osaga
10. dreamoon_love_AA

Hello, Codeforces!

I'm glad to invite you to amazing (we've tried to make it such) Codeforces Round #734 (Div. 3) which will start on Jul/23/2021 17:35 (Moscow time). This round is the first "trial of the pen" of me (MrPaul_TUser) and it seems to be hard to make it alone — a significant contribution was made by MikeMirzayanov, BledDest and DK318.

The round contains 6-7 problems. The difficulties of the problems are expected 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 1600 or higher, can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round, it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6-7 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) 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 trusted participants of the third division, you must:

• take part in at least two 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.

Thanks to WolfBlue, BlueDiamond, harlequen, -is-this-fft-, le.mur, Bench0310, Reiva5, Golovanov399 and Sho for testing the round and improving tasks.

Good luck and have fun!

UPD

Editorial