Hi all!

The second edition of the Blitz Cup is concluding this weekend! The final bracket is shown below. On Saturday, 10 matches were played with live commentary, and we watched quite a few tight fights! Recording is available on Youtube.

Final day

On Sunday, we're playing the remaining matches: two quarterfinals, two semifinals, and the final match! The schedule is as follows:

• Starting 12:05 UTC, tourist vs Ormlis Quarterfinals;
• 13:05 UTC, ecnerwala vs feecle6418 Quarterfinals;
• 14:05 UTC, Um_nik vs winner of (tourist vs Ormlis) Semifinals;
• 15:05 UTC, ksun48 vs winner of (ecnerwala vs feecle6418) Semifinals;
• 16:05 UTC, the final match!

Tune in at 12:00 UTC to the stream below to watch the action!

UPD

Congratulations to Um_nik, our Codeforces Blitz Cup 2026 Champion!

Hi Codeforces!

I have a great announcement for you. This month, we're holding the second Codeforces Blitz Cup! Remember all the WA1s and CEs we've seen from LGMs stressing out to submit before the opponent? They are coming back!

The Codeforces Blitz Cup is a single-elimination personal tournament where matches follow the special Blitz Rules. In short, each match is a 40-minute PvP contest, where problems open one by one, and only the first AC counts. The players can't use any help or prewritten code except a small template, and we get to watch them think and code live.

• Detailed rules
• Bracket

Check out last year's final rounds streams: day 1, and the final day 2 to get the feel for the format.

• Eligibility: Grandmasters or above
• Registration deadline: February 12, 10:00 UTC
• Elimination rounds: February 13th to 26th (free schedule)
• Live finals: February 28 to March 1 (online)

See you blitzing!

UPD

And we know our finalists! Congratulations to __baozii__, 244mhq, Amoo_Safar, Dominater069, ecnerwala, errorgorn, feecIe6418, Geothermal, ksun48, makrav, Ormlis, qiuzx, SSerxhs, tourist, turmax, Um_nik, and see you all on the livestream!

Hi Codeforces!

2025 comes to an end. However square the year was, we held a number of rounds: 29 Div. 1 and 31 Div. 2-only contests, to be precise! Additionally, 18 Div. 3, 4 Div. 4, and 13 Educational rounds made the schedule even more congested.

December is not only the perfect only time to wrap the year, but also to celebrate and thank all the people who made this year possible. That's why I want to highlight with this post the people whose efforts shaped Codeforces contests.

I'd like to say a huge thank you to every active community member who created and/or prepared problems for Codeforces rounds! Without your ideas and creativity, it would be impossible to hold so fun and interesting competitions. There are so many of you from every corner of the world, so that it's impossible to name everyone here, but one can see the authors of each contest on the contests page. Thank you!

Next, I'd like to extend my deepest gratitude to our coordinators who make sure rounds are the best quality and come on time. Here they are: Error_Yuan, maomao90, FairyWinx, Sugar_fan, satyam343, errorgorn, TheScrasse, 244mhq, Artyom123, Akulyat, Dominater069, flamestorm, abc864197532, cadmiumky, SSerxhs, Kaey, Vladithur, Um_nik, and Proof_by_QED coordinated Div. 1 and Div. 2 rounds this year. These people mostly worked after work of studies and sometimes even through the night to bring the rounds to you. An extra appreciation goes to Um_nik who now pre-reviews all round proposals, making sure the authors receive timely feedback. At the same time, BledDest and his team managed all the Educational rounds, Vladosiya managed all Div. 3 and Div. 4 rounds, with cry and soullless coordinating some of them. Thank you for your amazing work!

And last but not the least, I'd like to thank almost 800 testers who got to know the problems before the time, spotted some mistakes, and gave very useful advice to the problem authors. Again it's not possible to name them all, but huge shout-out to these heroes who tested the most rounds: _istil, chromate00, A_G, N_z__, larush, Error_Yuan, Proof_by_QED, Dominater069, __baozii__, Friedrich, -firefly-, madlogic, Um_nik!

Please join me in applauding all directly and indirectly mentioned people for their exceptional effort! Your work is invaluable for our community. Thank you! With that, I wish you all an exceptional New Year Eve and see you next year!

The harder 4 problems are from the Yandex Cup Finals.

Hi Codeforces!

On Dec/06/2025 11:15 (Moscow time) we will hold Codeforces Round 1069 (Div. 1) and Codeforces Round 1069 (Div. 2). Note the unusual starting time!

The harder problems of this round are based on the problems from the Final round of Yandex Cup 2025, Algorithms track, that will be held at the same time.

The problems are authored by v_vsg, heesooyaam, teraqqq, LeoPro, isaf27, elshiko, Flyce with guest problems from napstablook, sunkuangzheng, and great help from Vladithur, Dominater069, and tourist.

I'd like to thank Um_nik, Akulyat, okwedook, Merkurev, conqueror_of_tourist, Dominater069, cadmiumky, OG_Maksimchick4, Iguanado for testing the round, and MikeMirzayanov for the Polygon and Codeforces systems.

Because the official Yandex Cup Finals ends later than the round on Codeforces, the upsolving, solutions, and test cases will be closed until the end of the onsite contest, roughly 3 hours after the end of the Codeforces round. It is also forbidden to discuss the problems publicly until the end of the onsite round. Any comments here concerning the problems will be removed.

P.S. Same as with many rounds based on onsite contests, you can expect that the difficulty curve may be different from the one typical for Codeforces rounds. This is mostly connected with the limited amount of testing we can do to avoid problem leakage, and with the limited choice of problems. Nevertheless, I believe that it's better to have a round than not have one, and I hope you'll enjoy the problems!

Good luck!

Scoring distribution: you'll see in the contest.

UPD: there is live stream with problem discussions and comments here: https://www.youtube.com/watch?v=6R7iwYAXKLY

UPD2: Editorial.

Hi all!

The official Codeforces problemset contains more than $$$10\,000$$$ problems from past rounds. We try to prepare the problems as good as we can by the time we hold the round, but we don't have enough resources to also take care of them later on. As time goes, it can happen that older problems become broken in various sense. Also, some mistakes can be found. In the context of the new feature of sampling random problems, and the blitz type matches, I want to try to find and fix these problems.

Some of the issues can be identified automatically, but many can't. I'd like to therefore ask you to comment here with links to the problems that you find broken. Please use the [problem:1A] tags to link the problems like this: 1A - Theatre Square, and specify the issue. Examples of possible issues:

• Incorrect main solution.
• Incorrect tests.
• Severely inappropriate time or memory limits.
• Incorrect statement, or broken English. (Please don't include problems that may be not very easy to understand, but that don't have any formal errors in the statement.)
• Statement relies on the statements of another problem (e.g., the harder version's statement is not complete).
• Problem is not self-contained, requires some context (e.g., "Print the name of the contest.").

Do not include problems from language-restricted, April fool's, or marathon rounds.

To keep the comments organized, please don't duplicate the problems. However, I'd like to ask red members of the community (GM or higher) to verify or decline the issues suggested by lower-rated people, one verification per problem is enough.

Thank you!

Welcome to the final weekend of Codeforces Blitz Cup! More information about selection matches is available in this post, but we are now down to just 16 contestants! Here is how they will compete on Saturday and Sunday for the content and glory!

Saturday, March 8

1. turmax 25 : 20 b6e0: Mar/08/2025 13:00 (Moscow time) Scoreboard
2. errorgorn 31 : 2 izban: Mar/08/2025 14:10 (Moscow time) Scoreboard
3. isaf27 2 : 31 alireza_kaviani: Mar/08/2025 15:00 (Moscow time) Scoreboard
4. winners of 1 and 2: errorgorn 20 : 25 turmax: Mar/08/2025 16:00 (Moscow time) Scoreboard
5. Geothermal 35 : 10 jonathanirvings: Mar/08/2025 17:00 (Moscow time) Scoreboard
   ☕

6. heuristica 0 : 33 antontrygubO_o: Mar/08/2025 19:00 (Moscow time) Scoreboard

7. tourist 31 : 2 conqueror_of_tourist: Mar/08/2025 20:00 (Moscow time) Scoreboard
8. ksun48 20 : 13 Kuroni: Mar/08/2025 21:00 (Moscow time) Scoreboard
9. winners of 6 and 7: tourist 45 : 0 antontrygubO_o: Mar/08/2025 22:00 (Moscow time) Scoreboard
10. Golovanov399 33 : 0 induk_v_tsiane: Mar/08/2025 23:00 (Moscow time) Scoreboard

Sunday, March 9

• 11: winner of 3 and 5: alireza_kaviani 10 : 35 Geothermal: Mar/09/2025 15:00 (Moscow time) Scoreboard
• 12: winner of 8 and 10: ksun48 15 : 18 Golovanov399: Mar/09/2025 16:00 (Moscow time) Scoreboard
• 13: Semifinal: winner of 4 and 11: turmax 12 : 21 Geothermal: Mar/09/2025 17:00 (Moscow time) Scoreboard
• 14: Semifinal: winner of 9 and 12: tourist vs Golovanov399: Mar/09/2025 18:00 (Moscow time) Scoreboard Scoreboard2
• 14 rematch: tourist 27 : 18 Golovanov399: Mar/09/2025 19:20 (Moscow time) Scoreboard
• 15: Final match: winner of 13 and 14: tourist 45 : 0 Geothermal: Mar/09/2025 20:05 (Moscow time) Scoreboard

And the winner is

Congratulations tourist on winning the Blitz Cup 2025!

And huge thanks to lperovskaya, Vladosiya, tourist, MikeMirzayanov for organizing the event, as well as Egor and jonathanirvings for commentating most of the matches!

Tune into the live broadcast on youtube.com/@codeforceslive to see your favorite contestants compete and commentate!

Hi Codeforces!

As announced earlier, we’re holding an individual competition, the Codeforces Blitz Cup 2025, to celebrate 15 years of Codeforces. The tournament features PvP matches in a novel Blitz format, where every second (literally!) counts. In a 40-minute match, the opponents rush to solve each consecutive problem quicker than the rival. One needs to come up with a correct solution, think over the optimal implementation, and code cleanly: only the first one to get a problem correctly claims the points.

We’ve selected 64 strong participants who compete against each other in a single-elimination bracket. The first round has just concluded, and we’ve already seen both head-to-head battles and incredible comebacks. You can see some of the exciting screencasts of Round 1 in the streams section. Complete results (also shown below).

Starting today until Friday, Round 2 matches are held. Here’s the lineup:

• TheScrasse 3 : 30 conqueror_of_tourist Mar/06/2025 02:10 (Moscow time) Scoreboard
• Andreasyan 0 : 45 Geothermal Mar/06/2025 15:45 (Moscow time) Scoreboard
• StelIawinD 0 : 23 Golovanov399: Mar/06/2025 17:00 (Moscow time) Scoreboard
• lexiyvv 3 : 20 errorgorn: Mar/06/2025 18:00 (Moscow time) Scoreboard
• jonathanirvings 15 : 8 Egor: Mar/06/2025 18:00 (Moscow time) Scoreboard
• budalnik 16 : 17 alireza_kaviani: Mar/06/2025 20:00 (Moscow time) Scoreboard
• golomb 6 : 39 tourist Mar/06/2025 21:00 (Moscow time) Scoreboard
• SendThemToHell 0 : 23 ksun48: Mar/06/2025 23:10 (Moscow time) Scoreboard
• heuristica 33 : 0 Nikitosh: Mar/07/2025 00:00 (Moscow time) Scoreboard
• 353cerega 4 : 29 Kuroni: Mar/07/2025 09:00 (Moscow time) Scoreboard
• induk_v_tsiane 17 : 16 ecnerwala Mar/07/2025 10:00 (Moscow time) Scoreboard
• b6e0 20 : 3 244mhq Mar/07/2025 10:30 (Moscow time) Scoreboard
• isaf27 27 : 6 EnEm: Mar/07/2025 13:00 (Moscow time) Scoreboard
• paulzrm 0 : 33 turmax: Mar/07/2025 18:45 (Moscow time) Scoreboard
• izban 23 : 10 Kapt: Mar/07/2025 21:00 (Moscow time) Scoreboard
• peltorator 0 : 33 antontrygubO_o Mar/07/2025 21:00 (Moscow time) Scoreboard

We will stream featured matches of Round 2, and we encourage the participants to stream on their own. We’ll update the lineup above with the start time of the matches, so you can come and cheer!

On the weekend, March 8th and 9th, we’ll stream top 15 matches of the Blitz Cup. The streams will feature both opponents coding side by side, as well as commentary and discussion. Find the schedule of the final matches here and stay tuned in the streams section!

Hi Codeforces!

On Dec/03/2024 09:25 (Moscow time) we will hold Codeforces Round 990 (Div. 1) and Codeforces Round 990 (Div. 2). Note the unusual starting time!

The harder problems of this round are based on the problems from the Final round of Yandex Cup 2024, Algorithms track, that will be held at the same time.

The problems are authored by elshiko, Flyce, MrLolthe1st, sokolow, stepanov.aa, TeaTime, Tikhon228, webmonster, 4qqqq with guest problems from myst-6, Vladithur, BledDest and me.

I'd like to thank allvik66, Golovanov399, arbuzick, pperm, orz, AgafonovArtem, Qwerty1232, k1r1t0, Itsmylove1, Mak__, and errorgorn for testing the problems, tourist for helping with the round, and MikeMirzayanov for the Polygon and Codeforces systems.

Because of official Yandex Cup Finals ends later than the round on Codeforces, the upsolving, solutions, and test cases will be closed until the end of the onsite contest, roughly 3 hours after the end of the Codeforces round. It is also forbidden to discuss the problems publicly until the end of the onsite round. Any comments here concerning the problems will be removed.

Good luck!

UPD: The contest has been delayed to make sure the online contest does not start earlier than the onsite one.

Congratulations to the winners!

Div. 1:

1. jiangly
2. hank55663
3. noimi
4. cxm1024
5. Pyqe

Div. 2:

1. RGB_ICPC8
2. timer2024
3. madoka_savior
4. ylzxxx7
5. mion_sonozaki

UPD: You are free to discuss the problems now.

UPD: Editorial.

Hello Codeforces.

Unfortunately a few hours after the end of Round #819 we were pointed out that one of the problems was stolen from another online judge.

Codeforces team strongly condemns such an action from the author. By no means is this acceptable behavior. This is the first and the most important rule of problem making: your problem should be new up to your best knowledge.

A lot of people put lots of effort into creation of every single round. You can find these people mentioned in the announcements and they indeed deserve these acknowledgments. And yet a single cowardly decision can ruin this huge work and experience of thousands of participants.

In this particular case the copied problem was not widely known, and it seems that this made little or no impact on the course of the round. Nevertheless, we stick to the decision that in such case the round cannot be considered successful, and thus no rating changes can be applied. We will also remove the problem from the round and from the problemset as well as blacklist the author.

We hope that this case will be a lesson for future authors and this situation does not repeat in the future.

Hi all!

This weekend, at Dec/12/2021 18:15 (Moscow time) we will hold Codeforces Round 759 (Div. 2, based on Technocup 2022 Elimination Round 3). They are based on problems of Technocup 2022 Elimination Round 3 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.

The Div.2 edition is open and rated. Register and enjoy the contests!

• The round authors are: Denisson, antonis.white, dimatimoshin23, napstablook, kirill.grachoff
• Thanks Makcum888, snowysecret, stevancv, wxhtzdy, and ijxjdjd for testing.

Have fun!

UPD: congratulations to the winners!

Technocup 2022 - Elimination Round 3

1. LeoPro
2. princebelkovetz
3. DDima
4. pelmenner
5. abdula-mon-fon-alibaba-A

Codeforces Round 759 (Div. 2, based on Technocup 2022 Elimination Round 3)

1. Maria_Akizuki
2. maxlevel_spyofgame
3. zhaojianmin
4. FlameDragon
5. Shawn

The editorial is published.

Hi everyone!

The Final Round of Technocup 2021 starts this Sunday, March 21, 2021 at 13:00 MSK (10:00 UTC)!

For those who want to compete on the same problems, we will hold two regular Codeforces Rounds in the evening: one for the first division, and another one for the second. The rounds are starting at Mar/21/2021 16:20 (Moscow time).

If you are a participant of the official Technocup Finals, you are not allowed to take part in the rounds in the evening. We ask participants of the official Finals not to discuss the problems in open media till evening.

The problems are prepared by: Alexander Golovanov399 Golovanov, Evgenii amethyst0 Belykh, Andrey AndreySergunin Sergunin, Alexey Aleks5d Upirvitskiy, Diego Diegogrc Garcia and me.

Also huge thanks to Bench0310, kokokostya, Um_nik, dorijanlendvaj, brunomont, Stepavly, antontrygubO_o, JinhaiChen, budalnik, wucstdio, golikovnik, kuviman, dantrag, BledDest, Supermagzzz, ruanxiaoyu, geranazavr555, divanik, psevdoinsaf, Roms for testing and invaluable comments, and also to antontrygubO_o for the help in holding the mirror rounds.

Good luck!

Congratulations to winners of Codeforces Rounds!

Div. 1:

1. ecnerwala
2. Radewoosh
3. Benq
4. mango_lassi
5. AliShahali1382

Div. 2:

1. qwqc
2. gezlik
3. yanyutao
4. fengqiyuka
5. ykl

Thanks for participation! Editorial.

As you probably know, most of the rounds on Codeforces are created by active community members. We are very grateful to our talented authors from all around the world for bringing their ideas to tens of thousands of competitors, providing fun and learning experience for contestants of every expertise, from beginners to the world's top programmers. This post will cover the steps you need to take propose a round and become a problem writer on Codeforces.

Who can be a problem author

Best problems usually come from the most experienced participants. We have limited resources for rounds reviewing, so to make the process flawless for writers, starting January 1st, 2021, the following requirements for problem authors will be applied:

• rating: 2100 or above, or
• was a writer in the past.

The restrictions may be updated in the future, the post will be updated accordingly. If your round is already in the review status, don't worry, it will be reviewed regardless of the current restrictions.

If you are an experienced writer/jury member in other competitions, please write any current coordinator (listed below) a private message about your wish to prepare a contest and describe your experience in this area.

How to propose a round

If you meet the requirements, you should have the link "propose a contest/problems" in the personal menu on the right sidebar. Click on the link and follow the instructions carefully. Prepare and submit your proposal for a contest and problems.

In some time you will have a coordinator(s) assigned to your contest proposal. They will review your problems and you will discuss the problems with them. Please be active, respond to coordinators' questions in time, make the proposed changes quickly. Codeforces coordinators are very experienced participants and reviewers. Please respect their opinion, and note that they have the highest priority in any decisions on the problems.

Our coordinators are: Akulyat, 244mhq, satyam343, Kaey, FairyWinx, Sugar_fan, abc864197532, Dominater069, SSerxhs, Error_Yuan, Um_nik, cry, Proof_by_QED, and KAN.

You can only propose a whole problemset for a Div 2 or Div 1 + Div 2 round. We don't consider single problems. Also, we don't consider proposals for Div 3/4 or Educational rounds.

More details on the coordinating process and answers to some questions you can find here.

How to prepare problems

Problems for Codeforces rounds are prepared in Polygon. It is not recommended to prepare problems before the coordinator's approval, especially if it's the first time you propose a contest.

For each problem you will need to write a clear statement (in English or Russian), code a validator (a program that checks tests' correctness), a checker if necessary (a program that checks output), and of course correct solution. Also, you will need to create tests to check the contestants' solutions on. Your coordinator will do the statement translation if necessary, check your work, and suggests what to change and add if needed.

Before you start working on problems, even if you have experience working with Polygon, you must read these rules. All the work with checkers, validators, interactors, and generators is done with testlib.h library, you can read the introduction by the link and download examples from Polygon. Whenever you have any troubles and/or difficulties, contact your coordinator for help. It is much faster to do something right from the first time, then to do it wrong and then redo it again.

Writers reward

It is interesting and challenging work to invent and prepare problems but is also time-consuming and demanding work. That's why we pay authors for preparing problems for Codeforces. The rewards are:

The reward is paid in cryptocurrency.

Conclusions

We hope that with your help we will keep the regular stream of regular rounds full of fresh and interesting problems! If you have any questions on how to become a problem writer, ask in the comments. Please note that unrelated or outdated comments in this blog will be cleared once in a while to keep the blog and comments up-to-date.

Hi all!

This weekend, at Nov/29/2020 10:05 (Moscow time) we will hold Codeforces Round 687. It is based on problems of Technocup 2021 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 2021 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 problems authors are; amethyst0, eidan, Diegogrc, bensonlzl, ruanxiaoyu, antontrygubO_o, and KAN. Thanks to antontrygubO_o and 300iq for their help in coordination. Also huge thanks to testers for their invaluable help: Golovanov399, kalki411, malachi_toney_goat, dantrag, Retired_cherry, gigabuffoon, Andres_Alumets, firi., coderz189, Nero, GGMU, K0u1e, Bench0310, dorijanlendvaj, Um_nik, thenymphsofdelphi, Merkurev, kokokostya, wucstdio, smile_boi, abhishhh1!

Have fun!

Thank you for participation! We hope you enjoyed the problems. Congratulations to winners!

Technocup 2021 - Elimination Round 2

1. Kirill22
2. fastmath
3. VEGAnn
4. alexxela12345
5. solver777

Codeforces Round 687 (Div. 1, based on Technocup 2021 Elimination Round 2)

1. ecnerwala
2. ainta
3. Konijntje
4. al13n
5. kort0n

Codeforces Round 687 (Div. 2, based on Technocup 2021 Elimination Round 2)

1. Sharpness
2. iLoveIOI
3. Linqi05
4. xaohu
5. detect

Upd: Rating updates published.

UPD2: The editorial is published.

1119A - Ilya and a Colorful Walk

Author, preparation: 300iq.

1119B - Alyona and a Narrow Fridge

Author, preparation: KAN.

Aleks5d invites you to compete in the shortest solution challenge for this problem. His code (155 bytes):

[n, k], arr = [int(i) for i in input().split()], [int(i) for i in input().split()]
print([i for i in range(n + 1) if sum(sorted(arr[0:i])[::-2]) <= k][-1])

1119C - Ramesses and Corner Inversion

Author, preparation: 300iq.

1119D - Frets On Fire

Author, preparation: cyand1317.

#include <cstdio>
#include <algorithm>

static const int MAXN = 1e5;

static int n, q;
static long long s[MAXN];
static long long t[MAXN];

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%lld", &s[i]);

    std::sort(s, s + n);
    for (int i = 0; i < n - 1; ++i) s[i] = s[i + 1] - s[i];
    std::sort(s, s + n - 1);
    for (int i = n - 1; i >= 1; --i) s[i] = s[i - 1];
    s[0] = 0;
    for (int i = 1; i < n; ++i)
        t[i] = t[i - 1] + (s[i] - s[i - 1]) * (n + 1 - i);

    scanf("%d", &q);
    for (int i = 0; i < q; ++i) {
        long long l, r;
        scanf("%lld%lld", &l, &r);
        l = r - l + 1;
        int p = std::lower_bound(s, s + n, l) - &s[0] - 1;
        printf("%lld%c", t[p] + (l - s[p]) * (n - p), i == q - 1 ? '\n' : ' ');
    }

    return 0;
}

1119E - Pavel and Triangles

Author: gen, preparation: 300iq.

1119F - Niyaz and Small Degrees

Author, preparation: 300iq.

1119G - Get Ready for the Battle

Authors: Aleks5d, KAN; preparation: Aleks5d.

1119H - Triple

Author, preparation: RDDCCD.

Hello everyone!

The Final Round of Technocup 2019 starts today, on the March 3, 2019 at 11:00 MSK (08:00 UTC)! To watch live results (only pretests are considered!), follow the link below:

Results of Technocup 2019 Final Round

Congratulations to the winners of Technocup Final Round 2019!

1. Ildar 300iq Gainullin, Russia, Kazan'
2. Semyon cookiedoth Savkin, Russia, Dolgoprudnyy
3. Batyr 998batrr Sardarbekov, Kazakhstan, Almaty
4. Alexander scanhex Morozov, Russia, Saint Petersburg
5. Sofia Sonechko Melnyk, Ukraine, Kremenchuk

For those who want to compete on the same problems, we will hold two regular Codeforces Rounds in the evening: one for the first division, and another one for the second. The rounds are starting at Mar/03/2019 18:35 (Moscow time)!

If you are a participant of the official Technocup Finals, you are not allowed to take part in the rounds at evening. We ask participants of the official Finals not to discuss the problems in open media till evening.

Good luck!

The rounds are over. We sincerely apologize for the fail with the mirror rounds, we thought the editorial was only streamed to other sites of the olympiad, not online. You can read MikeMirzayanov's comment about the situation. I hope you enjoyed solving the problems even though they did not affected your rating.

Huge thanks to those people who worked on the problems for you, namely Alexander Golovanov399 Golovanov, Konstantin zemen Semenov, Daria Dashk0 Kolodzey, Mikhail Endagorion Tikhomirov, Ilia irkstepanov Stepanov and Denis Denisson Shpakovskij.

Also thanks to Um_nik, adedalic, demon1999, Roms, cdkrot, cyand1317, BledDest and Errichto for testing the problems, arsor for translating some of them into English, and cdkrot and arsijo for their help in conducting the mirror rounds.

Congratulations to the winners of the mirror rounds!

Codeforces Round 543 (Div. 1, based on Technocup 2019 Final Round)

1. Radewoosh
2. LHiC
3. vintage_Vlad_Makeev
4. natsugiri
5. V--o_o--V

Codeforces Round 543 (Div. 2, based on Technocup 2019 Final Round)

1. Diazzz
2. IhateProgramming
3. Kunal.h
4. galloska
5. deep_savani

Hi!

Tomorrow, at Feb/07/2019 16:35 (Moscow time) we will host Codeforces Global Round 1.

It is the first round of a new series of Codeforces Global Rounds. The rounds are open for everybody, the rating will be updated 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 2019:

• 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.

The problems of this round were developed by a team of authors: _h_, simonlindholm, grphil, vintage_Vlad_Makeev, GreenGrape, budalnik, cdkrot and me. Thanks arsijo and cdkrot for their help in the round's coordination, and also majk, pashka, Jeel_Vaishnav, Ashishgup and Jatana for testing the round!

Good luck!

Congratulations to the winners!

1. tourist
2. Um_nik
3. TLE
4. mnbvmar
5. sunset
6. EvenImage
7. ksun48
8. molamola.
9. snuke
10. fateice

Editorial.

Hi all!

This weekend, at Dec/23/2018 16:35 (Moscow time) we will hold Codeforces Round 528. It is based on problems of Technocup 2019 Elimination Round 4 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 2019 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 was prepared by Roms, Neon, BledDest, adedalic, awoo, isaf27, Endagorion with coordinator's help from 300iq.

Have fun!

Author, preparation: KAN.

Author, preparation: cdkrot.

Author, preparation: KAN.

Author, preparation: KAN.

Authors: MikeMirzayanov, cdkrot, preparation: cdkrot.

Author, preparation: Neon.

Author, preparation: KAN.

Author KAN, preparation: KAN, 300iq.

Huge thanks to cdkrot and 300iq for discussing the problems and general invaluable help in preparation!

Hi!

Tomorrow, at Nov/25/2018 19:35 (Moscow time) we will host the final round of Mail.Ru Cup 2018. The problems were authored and prepared by Codeforces team: me, Dmitry cdkrot Sayutin, Ildar 300iq Gainullin and Mike MikeMirzayanov Mirzayanov, and also Maxim Neon Mezhcheryakov. Huge thanks to Grigory vintage_Vlad_Makeev Reznikov abd Kamil Errichto Debowski for problems' testing!

This round is the final in the new championship called Mail.Ru Cup, you can learn more about it following the link. The round will be rated for everybody!

After the round we will know who will get the following prizes:

• First place — Apple MacBook Air
• Second and third place — Apple iPad
• Fourth, fifth, sixth places — Samsung Gear S3
• Traditionally, the top 100 championship participants will get cool T-shirts!

In each round, top 100 participants get prize points according to the table. The championship's result of a participant is the sum of the two largest results he gets on the three rounds. The results of the two first rounds are published here. In case of ties in the top six places, they will be broken by the sum of in-round scores in the corresponding (best for the participant) two rounds.

There will be eight problems and two and a half hours to solve them.

Good luck!

P. S. MikeMirzayanov invites everybody to the official Codeforces channel in Telegram: t.me/codeforces_official.

The round has finished, thanks everybody, hope you liked the problems!

Congratolations to the winners of the third round of Mail.Ru Cup 2018:

1. Radewoosh
2. V--o_o--V
3. ch_egor
4. ksun48
5. RAVEman

The results of the Cup will be announced shortly.

The editorial is here.

Hi all!

This weekend, at Nov/18/2018 19:05 (Moscow time) we will hold Codeforces Round 522. It is based on problems of Technocup 2019 Elimination Round 3 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 2019 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 was prepared by Alexander Golovanov399 Golovanov, Evgeny WHITE2302 Belyh, Alexandra demon1999 Drozdova, Arsenii craborac Kirillov, Ivan ifsmirnov Smirnov, Artem komendart Komendantian, Roman Roms Glazov, Daria Dashk0 Kolodzey and me.

Huge thanks to Grigoty vintage_Vlad_Makeev Reznikov, Ildar 300iq Gainullin, Ilia irkstepanov Stepanov, Andrey AndreySergunin Sergunin for testing.

Have fun!

The round is over, we apologize for the issues with platform accessibility. The round is declared unrated.

Congratulations to the winners!

Technocup 2019 - Elimination Round 3

1. 998batrr
2. Kuyan
3. paradox
4. ANTIMIRAGE
5. YaKon4ick

Codeforces Round 522 (Div. 1, based on Technocup 2019 Elimination Round 3)

1. ksun48
2. Anadi
3. LHiC
4. Um_nik
5. mnbvmar

Codeforces Round 522 (Div. 2, based on Technocup 2019 Elimination Round 3)

1. liriKl
2. Moysenko
3. okwedook
4. fauzdar65
5. Bismarck

Thank you all for joining!

The editorial is published.

Hi all!

This weekend, at Oct/21/2018 11:10 (Moscow time) we will hold Codeforces Round 517. It is based on problems of Technocup 2019 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 2019 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 Kostroma, Golovanov399, komendart, Denisson and Dashk0.

Have fun!

The round is over, congratulations to the winners!

Technocup 2019 - Elimination Round 2

1. Holidin
2. receed
3. Sonechko
4. radoslav11
5. scanhex

Codeforces Round 517 (Div. 1, based on Technocup 2019 Elimination Round 2)

1. Radewoosh
2. ainta
3. 300iq
4. TLE
5. RAVEman

Codeforces Round 517 (Div. 2, based on Technocup 2019 Elimination Round 2)

1. cz_yixuanxu
2. orbitingfIea
3. I_Love_Irelia
4. djq_fpc
5. buaads

The editorial is published.

Hi all!

This weekend, at Sep/23/2018 16:05 (Moscow time) we will hold Codeforces Round 512. It is based on problems of Technocup 2019 Elimination Round 1 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 2019 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 Elimination Round authors are Roms, BledDest and adedalic. Thanks to Anadi who authored the last problem for div. 1 round and arsijo for his help in coordination. This round would also be not possible without the help of our testers: winger, Um_nik, AlexFetisov, Denisson, thank you so much!

Have fun!

Div. 2 and the Elimination Round will feature 7 problems, preliminary costs are
250 — 500 — 750 — 1500 — 2000 — 2500 — 3000.

Div. 1 will feature 5 problems, preliminary costs are 500 — 1000 — 1500 — 2000 — 2500.

The round is over, congratulations to the winners!

Technocup 2019 - Elimination Round 1

1. 300iq
2. sadovan
3. voidmax
4. karasek
5. ----------

Codeforces Round 512 (Div. 1, based on Technocup 2019 Elimination Round 1)

1. TLE
2. webmaster
3. sunset
4. jcvb
5. volamtruyenkyii

Codeforces Round 512 (Div. 2, based on Technocup 2019 Elimination Round 1)

1. Chair_man_Xi
2. icecuber
3. yp155136
4. xjd0623
5. liyingyan7

The analysis is published.