Hello Codeforces!

flamestorm, MikeMirzayanov and I want to invite you to Codeforces Round 817 (Div. 4).

It starts on 30.08.2022 17:50 (Московское время).

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 behaviour. 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.

Many thanks to the testers: sandry24, SlavicG, tibinyte, Gheal, qwexd, haochenkang, TimDee.

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

Good Luck!

UPD 1: The contest is delayed by 15 minutes.

UPD 2: The opinions of testers about the order of problems are very contradictory. Please do not rely heavily on the order of problems in the round and read all the problems. Good luck!

UPD 3: Editorial is out!

Hello Codeforces!

On Aug/27/2022 17:35 (Moscow time) Educational Codeforces Round 134 (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:

Harbour.Space University has partnered with Vodafone Business, a company rich in tradition that specializes in telecommunications and with Oneragtime, a fund-as-a-platform specialized in sourcing, financing and scaling early-stage tech startups from across Europe, to offer motivated tech talents Master’s degree scholarships in Data Science and Front-end Development with combination of work experience.

Candidates will be working on the following tasks:

Data Scientist at Vodafone:

• Data Science: Descriptive and predictive analytics: selection, definition, and execution of adequate algorithms, models, tests, visualizations, etc.
• Technology: Selection, definition, and execution of adequate programming languages/frameworks, file formats, data storage solutions, automatic data flows, etc.
• Architecture: Define and/or follow best practices for Big Data & amp; Analytics use cases while extracting, transforming, storing, and feeding data to/from different data sources using on-premises solutions as well as public cloud services.
• Management: Report to project managers, clients, external and/or internal teams. Estimate resources and timelines for different tasks and follow up during the full project life cycle.
• Innovation: Awareness of and continuous training in state-of-the-art techniques, models, frameworks, and technical approaches to be applied to Data Science activities.

Front-End Developer at Oneragtime:

• Define the technology stack / tools to be used in the frontend
• Suggest projects that will improve the product or code base
• Write scalable, maintainable, reusable, and well-tested software that adheres to best practices
• Make technical time estimation on future software deliveries
• Document solutions with clear and concise explanations
• Collaborate with Product Owners, Growth Hacker, UX / Product Designers

All successful applicants will be eligible for a 100% tuition fee scholarship (22.900 €/year) provided by Vodafone Business for Data Science and by Oneragtime for Front-end Development.

CANDIDATE’S COMMITMENT

Study Commitment: 3 hours/day ‍ You will complete 15 modules (each three weeks long) in one year. The daily class workload is 3 hours, plus homework to complete in your own time.

Work Commitment: 4+ hours/day ‍ Immerse yourself in the professional world during your apprenticeship. You’ll learn from the best and get to apply your newly acquired knowledge in the field from day one.

University requirements

• Bachelor's degree in the field of Mathematics, Statistics, Data Science, Computer Science or similar
• English proficiency

Work requirements

Data Science:

• Advanced knowledge and experience in SQL, Python, Spark/Scala, and bash
• Experienced use of Big Data technologies: Spark, HDFS, Kafka, etc.
• Hands-on experience with Data Science techniques: feature engineering,

Front-end Development:

• Proficient in HTML/JSX, CSS, and with strong fundamentals in Javascript ES6
• Understand Vue
• Familiar with UX/UI principles: Figma
• Familiar with Webflow
• Expertise with Web pack, gulp, similar frontend build tools (npm)
• Proficient in unit testing tools e.g. JEST or similar tools
• Proficient in either Sass, LESS, TailwindCSS, Bootstrap, Flexbox, or similar tools
• Understanding of REST API
• Familiarity with Docker is appreciated
• Familiar with SQL works (Bonus: if you understand Postgre)

UPD: Editorial is out

Thanks a lot!

for Your participation

Hello, Codeforces!

We are glad to invite everyone to participate in Codeforces Round 816 (Div. 2), which will be held on Aug/20/2022 17:35 (Moscow time). The round will be rated only for the second division. You will have 6 tasks and 2 hours to solve them. We recommend you read all the problems.

Round is completely set by winter SIS (Summer Informatics School) students. During the camp we did our best to prepare interesting and creative problems. You can check previous rounds prepared by SIS students: Codeforces Round 815 (Div. 2), Codeforces Round #694, Codeforces Round #612, Codeforces Round #530

We are very thankful to

• task authors and developers: Vasilyev daubi Alexey, Denis Kapt Mustafin, Ivan __silaedr__ Podvorniy, Ilya ilyakrasnovv Krasnov, Evgenii pakhomovee Pakhomov, Mikhail MadProgrammer Zaytsev.

• to the wonderful teachers who made this round happen: Pavel PavelKunyavskiy Kunyavskiy, Dmitriy cdkrot Sayutin, Alesya AlesyaIvanova Ivanova, Konstantin kokokostya Makhnev

• Monogon for the great coordination, valuable advice, and patience

• KAN for the help during preparation of the contest

• Qwerty1232 for the help with the editorial

• testers for good proposals and important feedback: glebustim, kclee2172, AndreyPavlov, generic_placeholder_name, nor, TheScrasse, qualdoom, AlperenT, FairyWinx, vdv09, NToneE, KseniaShk, prost_sasha, agrayush13, kartikeyasri23, SomethingNew, and especially mejiamejia

• MikeMirzayanov and geranazavr555 for codeforces and polygon platform

Scoring distribution will be released before the contest begins

We hope that You will participate in our round, as well as in SIS!

Good luck and have fun!

UPD — Scoring distribution:

$$$500 - 1000 - 1750 - 2250 - 2750 - 3000$$$

The contest may contain interactive problems! Make sure to read this post.

UPD 2 — Editorial is out!

UPD 3 — Congratulations to the winners!

Official participants:

1. william556
2. fursuit
3. huge_waxberry
4. lbwhangbeateveryone
5. Longiseta

All participants:

1. jiangly
2. kotatsugame
3. hitonanode
4. ksun48
5. Rubikun

Hello, Codeforces!

We are proud to finally invite you to participate in Codeforces Round #815 (Div. 2), which will start on Aug/18/2022 16:35 (Moscow time). You will be given 5 problems, one of which contains a subtask and 2 hours to solve them. We greatly encourage you to read all the problems.

Round is completely set by SIS (Summer Informatics School) students. During the camp our students did their best to prepare interesting and creative problems. You can check previous rounds prepared by SIS students: Codeforces Round #612, Codeforces Round #530, Codeforces Round #694.

People who participated in the creation of the round:

• Problems are authored and prepared by: Kirill kirill.kligunov Kligunov, Gleb glebustim Ustimenko, Alexey daubi Vasiliev, Stanislav Death_on_2_Legs Alekseev, Vladimir plagues Gerasikov, Artem artem3605 Abaturov, Artem a.stepanov281005 Stepanov, Evgenii pakhomovee Pakhomov, Viktor robivirt Krivoschekov under the guidance of Mikhail meshanya Pyaderkin, Nikolay budalnik Budin, Philipp philmol Molodcov, Vladimir TeaTime Novikov, Fedor fastmath Ushakov.

• Special thanks for testing to: Dmitry Sweezy Pugachev, Alexey Mangooste Mikhnenko.

• And of course we want to thank our army of testers: alexxela12345, wabadabakalakaboo, fishy15, Kapt, rafaelka, alexchist, bashkort, Obeziana_Banana_Clown, Viktoriuss, PUFL, hoshiii, Vladosiya, anporf, elizazh.

• Coordinator: Artyom123

Also, we would like to thank:

• Artyom123 for the brilliant coordination.
• fastmath for improving one of the tasks!
• meshanya for improving the structure of the contest!
• MikeMirzayanov for great platforms, Codeforces and Polygon!

Scoring distribution: $$$500-1000-1250-(1500-1000)-2750$$$.

Good luck & have fun!

UPD1: Editorial

UPD2: Winners!

Div 2:

• Akemi-Homura
• First_Brave_Niuniu
• csyakuoi
• newbie__wrz
• sdfzzsy

Div 1:

• XiaoHa19672364
• -is-this-fft-
• Golovanov399
• Koosha_Mv
• Geothermal

Hello, Codeforces!

SomethingNew and I are glad to invite you to Codeforces Round 814 (Div. 1) and Codeforces Round 814 (Div. 2), which will take place on Aug/16/2022 17:35 (Moscow time). Each division will have 6 problems and 2 hours to solve them.

We would like to thank:

• 74TrAkToR for excellent coordination and for the idea of a problem for Div. 2.
• pakhomovee for idea and preparation of one of the problems for Div. 1, and for testing other problems of the contest.
• Um_nik, 244mhq, turmax, fedoseev.timofey, errorgorn, FairyWinx, daubi, arbuzick, AlesyaIvanova, Dart-Xeyter, Alexdat2000, Vladithur, rafaelka, plagues, LeoRiether, satyam343, ilya.kligunov, 1024mb, 127.0.0.1, efimovpaul, Prokhor08, marzipan, kirill.kligunov, MirMak, dmitry.lisitsyn, MichsSS, PUFL, bpaT_Kapaca, RomkaRS for testing the round and providing useful feedback.
• MikeMirzayanov for Codeforces and Polygon systems.
• ilaburkov for existing.

Score distribution:

Div. 2: 500 — 1000 — 1250 — (1250 — 1000) — 2500 — 2500

Div. 1: (500 — 500) — 1250 — 1250 — 2250 — 2250 — 2750

We hope that you will enjoy solving our problems!

Editorial

Congratulations to the winners!

Div. 2:

1. billieeyelash
2. randboy
3. TasselFlower
4. AVRush
5. Shiroqwq_

Div. 1:

1. tourist
2. maroonrk
3. Petr
4. ksun48
5. Radewoosh

Hi, Codeforces!

Igorfardoc and I are pleased to invite you to our Codeforces Round 813 (Div. 2), which will be held on Aug/13/2022 17:35 (Moscow time). This round will be rated for participants with rating lower than 2100.

We would like to thank:

• DishonoredRighteous for coordinating the round.
• Um_nik, Ormlis, errorgorn, FairyWinx, golikovnik, 74TrAkToR, thenymphsofdelphi, plagues, Kon567889, AlperenT, Alexdat2000, MagentaCobra, welleyth, GlowCheese, satyam343, thanhchauns2, SlavicG, _Vanilla_, jampm, QuangBuiCPP, LeCaToX for testing the round and providing useful feedback.
• MikeMirzayanov for Codeforces and Polygon.

You will be served 6 problems, one of which is divided into two subtasks, and you will have 2 hours and 15 minutes to sample them.

Hope you don't choke 😋

The score distribution is 500 — 1000 — 1500 — 2000 — (2000 — 750) — 3500

UPD: Tutorial

UPD2: Congratulations to the winners!

Div. 2:

1. iztrax
2. TrungNotChung
3. Akemi-Homura
4. bajablast
5. __NONE__

Div. 1:

1. tourist
2. m_99
3. jiangly
4. LJC00118
5. sjc061031

Hello, Codeforces.

Look what an interesting thing I've been working on the last few days. Now, if a problem uses test cases and its validator is written in the recommended way (using setTestCase), then the example inputs are displayed using different colors.

Just follow the link and see how beautiful it turned out: https://codeforces.net/contest/1714/problems!

So far I have enabled this only for the last few rounds, but if everything works as intended, I will enable it for more rounds.

In order to support this, I had to tinker a lot. I made changes to testlib.h so that the validator can return test markup. Support for this markup required changes in various system services. But I think it's worth it!

The coolest thing is that it was possible to implement all this without changing existing problems. If a validator is used using the setTestCase feature, then this improvement can be applied to this problem.

Of course, it would be cool to have similar highlighting in example outputs as well. And even, say, synchronously highlight an input-output test case pair when hovering over. Unfortunately, standard checkers are often used, in which information about test cases is lost. Perhaps I'll apply some heuristics to make it work in most cases.

Hi Codeforces!

GlowCheese, DeMen100ns, SPyofgame and I are delighted to invite you to participate in Codeforces Round #812 (Div. 2).

• Start time: Aug/06/2022 17:35 (Moscow time)
• Duration: 120 minutes.
• Number of tasks: 6, including at least one interactive problem. Make sure to read this blog and familiarize yourself with these types of problem before the round!

Special thanks to:

• errorgorn for wonderful coordination by rejecting 50+ problems from me, all for a better Codeforces.
• KAN for translating our statements.
• Vip testers: satyam343, tfg.
• The great great coordinators that tested our round: antontrygubO_o, 74TrAkToR.
• DeMen100ns for providing amazing problems, which helped us a lot.
• GlowCheese and SPyofgame for their great effort, for pointing out mistakes in the original intended solutions.
• _FireGhost_ and neko_nyaaaaaaaaaaaaaaaaa for spending time helping us while they have to organize VNOI CUP 2022.
• Our testers: thenymphsofdelphi, neko_nyaaaaaaaaaaaaaaaaa, generic_placeholder_name, Andreasyan, PurpleCrayon, tfg, BucketPotato, Vladithur, _FireGhost_, LetterC67, satyam343, 18o3, 1DWalker, vangtrangtan, haong, Megumin2006, dinhsangBKA, QuangBuiCPP, Etherite, nyagami, Hehe, sonoobIdie, hydroshiba, LeCaToX, makyuri.ami.
• MikeMirzayanov for amazing platforms Codeforces and Polygon.
• Last but not least, you for your participation and being WA, then dropping at least one color :P

The score distribution is 500-1000-1750-2000-2500-3000

Hope to see you in final standings!

UPD: We have a small gift for a Vietnamese participant who have the highest score, so if it is you, please DM me after contest. Good luck everybody!

UPD2: Editorial

UPD3: Congratulations to the winners!

Div.2:

1. RGB_ICPC7

2. Xylenox

3. 5cd

4. Jason2022

5. Imot

Div.1 + 2:

1. peti1234

2. A_G

3. kotatsugame

4. jiangly

5. Rubikun

Hello Codeforces!

On Aug/04/2022 17:35 (Moscow time) Educational Codeforces Round 133 (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:

Harbour.Space's Front-end Development programme is where programming and creativity collide. Receive up to a 50% scholarship and take advantage of this opportunity to study in Barcelona and learn from industry experts while you become one yourself.

The programme is heavily geared towards developing students’ professional skills needed for employment while being able to adapt to rapidly changing technology.

So let's meet your programme leaders:

Hjörtur is the CEO of 14islands, a design and development studio from Stockholm in Sweden and Floripa in Brazil. He co-founded the studio in 2011 and since then they've done work with companies such as Google, Adidas, Disney, Facebook, HBO, Shopify, Ericsson and many innovative startups in the world.

Marco Barbosa is the Managing Director of 14islands, a design and development studio from Stockholm in Sweden and Floripa in Brazil. Their projects have won multiple awards such as the FWA, Awwwards, CSS Design Awards, and European Design Awards.

Good luck,

Harbour.Space University Team

UPD: Editorial is out

Hello, Codeforces!

Take a look on excellent news from TON Foundation about TON Smart Challenge.

Please note that this contest will not take place on Codeforces. It is about smart-contracts, not traditional algorithmic problems. But in the last similar competition, the competitive programmers were among the winners!

I pass the floor to the TON team.

The next edition of the TON Smart Challenge contest for programmers is slated to begin on Aug. 4 with a total prize pool of 16,000 Toncoin.

TON Foundation developers have carefully reviewed and considered feedback from participants of the first TON Smart Challenge and will make quality-of-life improvements for the upcoming second part of the competition.

The TON Smart Challenge #2 is aimed at developers just starting their journey of learning FunC, the primary programming language for The Open Network blockchain, and will comprise five simple tasks, which will be checked automatically.

To participate, you must register by going to this website.

You can find more details and news on the competition on the TON Contests Telegram channel.

You can prepare for the competition by studying the documentation section and creating a developer’s environment.

Hurry up, don't miss your chance!