Hello! Codeforces Round 756 (Div. 3) will start at Nov/25/2021 17:35 (Moscow time). You will be offered 7-8 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 ACM-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 7-8 problems and 2 hours and 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 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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of our work. Problems have been created and written by ITMO University teams: MikeMirzayanov, MisterGu, myav, Vladosiya, Aris, senjougaharin and me Gol_D.

Also many thanks to God_Of_Code, oversolver, FlakeLCR, Igorjan94, Jester, KHiMAeRA, KerakTelor, Loolo, MatheusMonteiro, Resende, I_love_kirill22, dedlocc, doreshnikov, kbats183, kocko, vsinitsynav and pashka for testing the contest and valuable feedback.

Good luck!

UPD: Editorial

Hello, Codeforces!

On Nov/23/2021 17:35 (Moscow time) we will host Codeforces Global Round 17.

It is the fifth round of a 2021 series of Codeforces Global Rounds. The rounds are open and rated for everybody.

The prizes for this round:

• 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!

The problems were written and prepared by AliShahali1382(Ali Shahali), AmShZ(AmirMohammad ShahRezaei), DeadlyCritic(MohammadHossein Paydar), Keshi(Alireza Keshavarz), alireza_kaviani(Alireza Kaviani).

We would like to thank these people:

• antontrygubO_o, for coordinating and helping a lot to make this round happen.
• Tet(Soroush Sahraei) and Davoth(Alireza Samimi) for giving ideas for some problems.
• our testers for testing and providing helpful feedbacks: gamegame, Kalam, Amoo_Safar, prabowo, dorijanlendvaj, aarr, ymmparsa, nor, ArshiaDadras, Davoth, ijxjdjd, sohsoh, 16204, wxhtzdy, naman1601, mblazev, fatemetmhr, hiva_, manish.17, Saman., SMahdi, Vjovein, mohammad_rastegar.
• again gamegame for being an orz tester and ACing all of our problems!
• MikeMirzayanov for codeforces and polygon platform!

You will have 3 hours to solve 9 problems. As usual, it is highly recommended to read all problems!

The score distribution will be announced at least 5 minutes before the round starts! :)

Score distribution : 500 — 1000 — 1500 — 2250 — 2500 — 2750 — 3250 — 3500 — 4000.

Editorial is out

Hello Codeforces!

On Nov/22/2021 12:35 (Moscow time) Educational Codeforces Round 117 (Rated for Div. 2) will start.

The problems are based on the Southern Russia and Volga Cup 2021, which is a regional contest of ICPC. If you have participated in it or are planning to play it as a virtual contest, please refrain from taking part in the Educational Round.

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, 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.

Hi all!

This weekend, at Nov/14/2021 09:05 (Moscow time) we will hold Codeforces Round 755 (Div. 1, based on Technocup 2022 Elimination Round 2) and Codeforces Round 755 (Div. 2, based on Technocup 2022 Elimination Round 2). They are based on problems of Technocup 2022 Elimination Round 2 that will be held at the same time.

Technocup is a major olympiad for Russian-speaking high-school students, so if you fall into this category, please register at Technocup website and take part in the Elimination Round.

Div. 1 and Div.2 editions are open and rated for everyone. Register and enjoy the contests!

• The round authors are: Denisson, antonis.white, dimatimoshin23, __JustMe__, 4qqqq, Aleks5d
• Coordinator: isaf27
• Thanks KAN for help with round preparation, also thanks MikeMirzayanov for the great Codeforces and Polygon systems.
• Thanks ptd, Makcum888, Monarcle, Monogon, manish.17, gjaiswal108, mathusalen for testing.

Have fun!

The scoring distribution:

• Technocup: 500 — 500 — 1000 — 1500 — 2000 — 2500 — 3250
• Div1: 500 — 1000 — 1500 — 2000 — 2750 — 3750
• Div2: 500 — 500 — 1000 — 1500 — 2000 — 2500

The round is over. Congratulations to the winners:

Technocup

1. Artyom123
2. turmax
3. I_love_teraqqq
4. strapple
5. Kapt

Div1

1. ko_osaga
2. maroonrk
3. xay5421
4. jiangly
5. uwi

Div2

1. 1443356159
2. int65536
3. strongerthanspeed
4. DSair
5. nunu03

Editorial

Henlo Codeforces!

We are very glad to invite you to the Codeforces Round 754 (Div. 2), which will be held on Nov/12/2021 17:35 (Moscow time). This round will be rated for participants with a rating less than $$$2100$$$. For higher rated participants, we challenge you to solve problem F ;)

All the problems were authored and prepared by Ashishgup, the_hyp0cr1t3, ExplodingFreeze and me. We have tried our best to create an interesting problemset with clear statements. Hope you enjoy the round :D

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

We would like to thank:

• antontrygubO_o for his amazing coordination and help in improving our problems.

• Our army of testers: Um_nik, 244mhq, Monogon, _runtimeTerror_, Jeel_Vaishnav, AmShZ, errorgorn, ijxjdjd, Utkarsh.25dec, Dragnoid99, yash_daga, Vivek1998299, taran_1407, MagentaCobra, Retired_cherry, sinus_070, AC_007, talibmohd, KahanHai, Dragonado, Submit_Galactic_Algo, KeyurJain, tvcv901, ekanshi, Jellyman102, jimmy18, inferno14 for testing the round and providing valuable feedback.

• MikeMirzayanov for the Codeforces and Polygon platforms.

Here's the scoring distribution of the round:

$$$500 - 1000 - 1500 - 2000 - 2500 - 3500$$$

UPD: Editorial is out

Also, congratulations to the winners.

Div 1 + 2:

1. SSRS_

2. Vercingetorix

3. MatikaneTannhauser

4. codinglunch

5. hank55663

Div 2:

1. MatikaneTannhauser

2. codinglunch

3. huyinghao0706

4. QuietBeautifulThoughts

5. MyBotDear

Hello Codeforces!

Once again, we are glad to invite you all to Codeforces Round 753 (Div. 3), the third division round held on Nov/02/2021 17:35 (Moscow time). This round was prepared (again) by me and MikeMirzayanov. The problems are different but our anticipation is the same :) Hope you will like the problems we've prepared!

Big thanks to MikeMirzayanov for great ideas as well as for helping me with writing good statements and better tests. I'm still a bit slow with some aspects of preparing problems so it's a really noticeable help for me. (UPD: as of this moment, it became much more noticeable, so, really, thanks a lot!)

Also special thanks for testing the round to RisingWizard, Capta1n_Shy, Mazaalai, GustavoMG, nizamoff, 2020akadaver, ashmelev, p0kemanbr, Kofta and, as usual, to Gassa for valuable comments! And last but not least, thanks to everyone who'll be participating! This round contains 8 problems and is expected to have a decent level of difficulty 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 tests strong enough but it doesn't at all guarantee that open hacks phase will be pointless.

You will be given 8 problems and 2 hours to solve them. We remind you that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes. Also please note that the number of problems has slightly increased since the last edit.

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.

Good luck to everyone!

UPD: Editorial is out!

UPD: (28 April, 2022)

আবার চলে এসেছি! (That's Bengali for "I am back! (in Terminator mode)")

I am super excited to invite you to participate in Codeforces Round 752 (Div. 1) and Codeforces Round 752 (Div. 2) which will be held on Oct/30/2021 17:35 (Moscow time). This round is rated for both divisions.

You will be given $$$6$$$ problems in each division and $$$2$$$ hours to solve them. All the problems are authored and prepared by me.

I would like to thank -

• antontrygubO_o for his breathtaking(literally) coordination of the round. no funny text this time
• Alpha_Q, Anachor and antontrygubO_o for putting up with my dumb ranting and helping with the problems.
• Um_nik, gamegame, 244mhq, dorijanlendvaj, upobir, _Ash__, Anachor, Arg_007, Alpha_Q, steinum, Tasdid, t17, imAnik, Alfeh, Aritra741, SajidZakaria, YoyOyoYOy000y000, SlowDecay, ijxjdjd, flamestorm, ovis96, 16204, and Urvuk3 for testing the round.
• dorijanlendvaj for providing a test case which will potentially prevent few wrong solutions from getting AC.
• The great MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• You, for existing and participating in the round. Also, thanks for giving your best and not quitting. You will eventually be happy . Just hold right there.

The statements are short and directly ask you what to do and I have tried to make the pretests strong. I highly encourage you to read all the problems.

Solve problems and help the poor! Yes, you heard it right, this time you can help the world by just solving problems. I will donate money based on the solve count of each problem by the following measure:

Div2A - 0.005 USD
Div2B - 0.006 USD
Div2C/Div1A - 0.008 USD
Div2D/Div1B - 0.01 USD
Div2E/Div1C - 0.04 USD
Div2F/Div1D - 0.2 USD
Div1E - 2 USD
Div1F - 2 USD

The total estimated money is half of what I will get from Codeforces for this contest(but you can make it more by just solving more problems!). I am a student, so pardon me if that's too little.

Also, did you know that you can still upvote my The Ultimate Topic List blog and make it to the top?

Finally, I would like to dedicate this contest to me! I want to thank me for believing in me, for doing all this hard work, for trying to do more right than wrong. I want to thank me for just being me at all times.

Score distribution:
Div.1: $$$750-1000-1750-2500- 3500-3750$$$.
Div.2: $$$500-1000-1750-2000-2750-3500$$$.

Good Luck! Love you .

UPD: Editorial

UPD: Congratulations to the winners.

Div.1:

1. tourist
2. djq_cpp
3. Petr
4. DmitryGrigorev
5. ecnerwala

Div.2:

1. Rolling_Code
2. Pecans
3. fangzhijina2020
4. whtdsjmr
5. Graphcities

UPD: Here is how the donation amount looks like:

Div2A - 0.005 * 9529 = 47.645 USD
Div2B - 0.006 * 6274 = 37.644 USD
Div2C/Div1A - 0.008 * (4012+967) = 39.832 USD
Div2D/Div1B - 0.01 * (2273+911) = 31.84 USD
Div2E/Div1C - 0.04 * (27+396) = 16.92 USD
Div2F/Div1D - 0.2 * (1+24) = 5 USD
Div1E - 2 * 8 = 16 USD
Div1F - 2 * 3 = 6 USD

Total - 200.881 USD

FYI I will get 400 USD for this contest. So the donation amount is indeed half of this as I have estimated before the contest, although didn't think that it would be this accurate.

I will update you again when I get the money from Codeforces, more likely after a few months as I haven't received my previous contest's payment yet which happened 3 months ago!

Also, thanks for being a part of this. You have just helped someone who is in need (I mean after I distribute the money).

Hello Codeforces!

On Oct/29/2021 17:35 (Moscow time) Educational Codeforces Round 116 (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, 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.