Hello, Codeforces!

I am glad to invite everyone to participate in Codeforces Round #837 (Div. 2) , which will be held on Sunday, December 11, 2022 at 17:35 UTC+2.

The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially in the round.

You will be given 6 problems and 2 hours to solve them. This round was prepared by me and 4qqqq.

I'd especially like to thank:

• Aleks5d for awesome coordination of our round.
• MikeMirzayanov, for the amazing Codeforces and Polygon platforms.
• I_Remember_Olya_ashmelev, TurboPiKachu, divanik, olya.masaeva, nnv-nick, neohacker, PavelKorchagin and Kolychestiy for testing the round and providing valuable feedback.

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

The score distribution will be announced shortly before the round (or earlier).

We wish you good luck and high rating!

Hello!

Tomorrow (December 7th) the ICPC Northern Eurasia Finals (previously known as NEERC) will take place. The competition will be held at several venues: St. Petersburg, Barnaul, Kutaisi and Almaty. Almost 300 teams will take part in it.

We invite you to join the online mirror of the competition: 2022-2023 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC Rules, Teams Preferred). It will start at Dec/07/2022 11:05 (Moscow time). We recommend participating in teams, but experienced individual participants will also have fun.

The duration of the competition will be 5 hours. Of course, the round is unrated.

Good luck!

Hello, Codeforces!

Great news! Here's another opportunity to take a part in an exciting event from our main sponsor.

The contest for smart contract developers with a total prize fund of 50,000 TON begins on 2 Dec. 12:00 UTC and lasts until 23 Dec. 18:00 UTC. TON Smart Challenge #3 will be suitable for experienced developers as well as for beginners that are ready to dive into FunC.

TON Smart Challenge #3 tasks will be dedicated to the basic aspects of how smart contracts work in TON: complex manipulations with cells, organizing the storage of smart contracts, working with comments, basic cryptography and the logic of governance smart contracts.

A contest aimed at optimization of 5 smart contracts written in the FunC language native for The Open Network blockchain. The goal of the contest is to optimize contract execution cost, preserving functionality and business logic. One may find more information about development in TON here.

Register through the @toncontests_bot to be notified, when it starts, and stay up to date

Hello, Codeforces!

We are happy to invite you to the great event the 45th ICPC World Finals Challenge powered by Huawei，which will start on November 17, 2022, 00:00 UTC (UTC+0).

In this Challenge, You will have a unique chance:

• to compete during 14 days online challenge;
• to solve 1 or 2 problems prepared by different business domains of HUAWEI;
• to win amazing prizes from HUAWEI!

As a special prize, HUAWEI together with ICPC Foundation will provide the travel trip to the 46th Annual ICPC World Finals in a guest role to the 2 winners (1 winner for each problem)!

Everybody is welcome to participate. It is an individual competition.

45th ICPC World Finals Challenge powered by Huawei (open to public):

Start: November 17, 2022 00:00 UTC (UTC+0)
Finish: November 30, 2022 23:59 UTC (UTC+0)

This time HUAWEI has prepared 2 challenging tasks for you from different business domains – Central Software Institute and HiSilicon. You are free to choose which problem you would like to solve, and you are also welcome to solve both problems, but please remember the total runtime of both rounds, which start simultaneously, is 14 days only. We hope you'll enjoy this complex yet very exciting Challenge!

Each problem will have own scoreboard and own prize fund, so this is a unique chance for you to win double prize for two solved problems!

Problem No 1: Parameterized Branch Instruction Stream Generation

Benchmarks are popular for estimating and comparing the performance of computer systems which has always been a challenging task faced by computer architects and researchers. However, it is known that as emerging applications evolve, benchmark characteristics drift with time and an optimal design using benchmarks of today may not be optimal for applications of tomorrow. This problem has been aptly described as: “Designing tomorrow’s microprocessors using today’s benchmarks built from yesterday’s programs”. One of the approaches for addressing these challenges is to complement application benchmark suites with synthetic benchmarks.

Program control flow generation algorithm is one of the most difficult questions for synthetic benchmarks. Hence, this problem focuses on generating program control flow for synthetic benchmarks based on MIC related to behavior of conditional branch instructions. In this question, program control flow generation is abstracted to draw a route on a directed graph. The route and the graph with MIC closest to the input will be the winner.

Problem No 2: Task Scheduling and Data Assignment

This is a problem about job scheduling and data assignment. Consider a scenario, where we want to run a complicated software project, on a computing cluster or on a multi-core heterogeneous computing chip. The computing cluster has multiple computing units of various computing power, as well as multiple memory disks with various reading and writing speed. The software project consists of many small computing tasks with inter-dependence among them. During the execution, these tasks will also produce data that need to be stores onto some memory disks. Our goal is to design an efficient task scheduling algorithm, that is able to assign the tasks to different computing units, and to store the data to different memory disks, such that the overall makespan, which is the time the finish the last task, is minimized. As you can imagine, usually when a task starts its execution, it needs to first read the necessary data from the memory disks, and when the computation completes, it will then write its own data to some memory disk for other tasks to read. This means, the schedule of tasks to computing units, and the assignment of data to memory disks are tightly connected to each other, and they will together decide the overall running time of the whole software project.

Prizes

Challenge Rules and Conditions

By participating in this Challenge, you agree to the Challenge Rules and Conditions of Participation

Good luck, we hope this will be fun!

Hello Codeforces!

The Southern and Volga Russian Regional Contest was held in Saratov State University on 22nd of November. This contest was used to qualify the teams from Southern Russia and Volga region to the Northern Eurasia Finals.

On Nov/27/2022 13:35 (Moscow time), we will conduct the online mirror of this contest. It will last for 5 hours and is best suited for teams of three people, although it is not forbidden to participate in teams of smaller/larger size. The mirror will use ICPC rules, the same as the offline contest.

I would like to express my gratitude to all other jury members: awoo, Neon, vovuh, adedalic, DmitryKlenov, dmitryme, DStepanenko, elena and kuviman. Also, big thanks to the contest testers: IlyaLos, Oleg_Smirnov, I_Remember_Olya_ashmelev, pashka, and especially MikeMirzayanov not only for testing the problems, but also for his excellent Polygon system, without which it would be almost impossible to prepare the competition.

As a chief judge of the contest, I hope you enjoy the problems!

Of course, the contest will be unrated.

upd: The editorial can be found here.

Hello Codeforces!

On Nov/26/2022 17:05 (Moscow time) we will host Codeforces Global Round 24. Note the unusual time of the round.

It is the sixth round of a 2022 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 2022:

• 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 2022 supported the global rounds initiative!

The problems were written and prepared by Cocoly1990, waaitg and Imakf. 👀👀👀

We would also like to thank:

• errorgorn for 🥵 and 🥶 coordination.
• KAN for translating the problems. 🥳🥳🥳
• Wolam for proposing rejected problems. 😭😭😭
• Our testers for testing and providing invaluable feedbacks: Rebelz, Heltion, ShmilyTY, dXqwq, Aestas16, SSerxhs, Qiuly.qwq, Leasier, Yakumo_Ran, Nanako, Celtic, JohnVictor, installb, mafailure, CuiZhenhang, lunchbox, pedroslrey, Wolam, LLL_2820, mejiamejia, TomiokapEace, QAQ_QWQ, mkisic, Mahfel, luanmenglei, ak2006 and veco. 😋😋😋
• MikeMirzayanov for amazing platform Codeforces and Polygon. 🥰🥰🥰

Round Information:

• Duration: 2 hours and 30 minutes 🔥🔥🔥
• Number of problems: 8 problems, one split into 3 subtasks 🤯🤯🤯
• Score distribution: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$1750$$$ — $$$2250$$$ — $$$2250$$$ — $$$(2000+500+500)$$$ — $$$3500$$$ 🤤🤤🤤
• There is an interactive problem, so please see the guide of interactive problems if you are not familiar with it. 🤭🤭🤭

As always, hope you all gain non-negative ratings $$$\Delta$$$ in this round! 🍾🍾🍾

UPD1: Editorial

Hi again, Codeforces!

fishy15, flamestorm, ScarletS, saarang and I are glad to invite you to our second Constructiveforces round, Codeforces Round #836 (Div. 2), which will be held on Nov/25/2022 18:35 (Moscow time). The round will be rated for participants with rating lower than 2100.

Please note the unusual time!

We'd especially like to thank:

• errorgorn and KAN, for their fantastic coordination and translation of the round!

• MikeMirzayanov, for creating the amazing Codeforces and Polygon platforms!

• Our testers dorijanlendvaj, PurpleCrayon, Sexpert, atodo, maomao90, prvocislo, nor, AlperenT, polarity-, KrowSavcik, idk321, SlavicG, epicxtroll, Nahian9696, Beacon, borbrudar, _Vanilla_, Competencia, Awesome3.14, juanpabloamezcuagonzalez, anishde85, coder_sounak, jampm, Codula, ak2006, IAmTheHazard, and bakekaga for testing the round, catching any mistakes and providing lots of valuable feedback! We tried to get a large range of testers with different coding experiences so that everybody enjoys the round.

• And you, the contestant, for taking part in and hopefully enjoying our contest!

You will have 2 hours to work on (and solve!) 6 problems. At most one of the problems will be interactive. Make sure to read this blog and familiarize yourself with these types of problems before the round! You are highly encouraged to read all the problems ;).

The scoring distribution is $$$500-1000-1500-1750-2250-3000$$$.

Good luck, and see you on the scoreboard!

UPD1: Thanks to ak2006 for making video editorials for some of the problems.

UPD2: Editorial is out!

UPD3: Congrats to the winners:

Div. 1 + 2:

1. jiangly
2. SSRS_
3. kotatsugame [tie]
4. Maksim1744 [tie]
5. March_7th

Div. 2:

1. March_7th
2. is_this_Furry
3. puffins
4. DongXuelian
5. ouqI

Hello Codeforces!

mesanu, flamestorm, MikeMirzayanov and I are glad to invite you to Codeforces Round #835 (Div. 4)! It starts on Nov/21/2022 17:35 (Moscow time).

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 would like to thank:

• RedstoneGamer22, tibinyte, haochenkang, badlad, down, borbrudar, Phantom_Performer, tolbi, AlperenT, Bakry, prvocislo, Gheal, keta_tsimakuridze, KrowSavcik, BucketPotato, pashka, MikeMirzayanov for testing the round!

• Max_Calincu, TimDee, MikeMirzayanov for helping with Russian translations!

We suggest reading all of the problems and hope you will find them interesting!

Good luck!

UPD: Editorial is posted.