Hello Codeforces!

Contest 2050 and Codeforces Round #718 (Div. 1 + Div. 2) will take place on Apr/23/2021 17:35 (Moscow time). It's rated for everyone! The score distribution is 500--1250--1500--1750--2500--3000--3000--4000. You will have 2 hours and 45 minutes to solve 8 problems.

Contest 2050 is initiated by volunteers of the 2050 Conference. You can find out what is 2050 at the end of this blog.

The contest is prepared by

• Fulisike, littlelittlehorse, Retired_MiFaFaOvO, xyz2606

and we'd like to thank

• KAN, Nebuchadnezzar for their excellent coordination.
• absi2011, chitanda, Gromah, Itst, _cherry_, Aaeria, HIS_GRACE, A.K.E.E., namanbansal013, Miracle03, yaoR, sshwyR, chenjb for testing the round.
• MikeMirzayanov for the great codeforces and polygon platforms.

See you on Friday and good luck!

We have the following introductory message by the 2050 volunteers:

2050 aims to equip young people to take action and to become volunteers. Every 'last weekend' of Apr, together with the youth, we celebrate the technology at Yunqi Town, China. 2050 is a volunteer-only, not-for-profit unconference.

"Most of the conferences in China are held for those who are already successful in their careers, but none targets young people. 2050 wants to fill the gap, giving Chinese youth a stage to make their own voices heard and maximize their energy and talent," said Dr. Wang Jian.

What to expect at 2050?

At 2050, we call it containers. There are 10 containers: 2050 Youth; Migratory Bird Program; Game On; Mindnet; Youth Stage; Starry Night Camping; Everything Grows; Explorer Space; New Gen Forum; Youth Reunion.

Special arrangement of this year

This year, because of the pandemic and travel restriction, many friends from overseas cannot join us in Hangzhou. This however, cannot stop us from connecting with each other. 2050 will be connecting with 100 cities, to dial in volunteers who cannot join us onsite.

The road to championship @ new gen forum

Algorithms and programming are their pleasures of life. With the belief of victory, they defeated the most powerful opponents. They worked hard to explore the boundaries of human intelligence on the road to the ultimate. We invite the top competitive programming players around the world to share their journeys on Saturday at 23:00~24:00 (UTC+8). If you are interested, please message littlelittlehorse.

Find out more at https://2050.org.cn/en/.

UPD. Score distribution 500--1250--1500--1750--2500--3000--3000--4000

UPD Congratulations to the winners

1. Benq
2. Um_nik
3. mnbvmar
4. Radewoosh
5. y1s1

Editorial

Editorial

Rucode Festival is a great opportunity to prove yourself and get experience in programming competitions. The Championship will be held on 25 April in two different levels of complexity: for A/B divisions and for C/D divisions. The tasks will be in English and in Russian.

We welcome teams from 1 to 3 people.

The tasks are made by the leading Russian universities professors, champions of international competitions and coaches of Moscow Workshops.

To take part please register here until 24 April, 23:59 (Moscow)

Schedule:

• Trial round: 10:30 — 11:00

• Contest: 11:00 — 16:00

See you at #RuCode!

It's me again!

Codeforces round #717 will take place on Apr/21/2021 16:35 (Moscow time), an hour early than the usual timing. It's rated for the second division, but, as usual, first division participants can take part out of competition.

The problems were created by me, and some of them are based on the Egyptian IOI qualification. I'd like to thank:

• KAN and Aleks5d for their excellent coordination.
• Akulyat, __cucumber__, Randle, Riladavin, Waley, MForest, _Stefan_, RabbitPower, and the official contestants, I guess, for testing the round.
• MikeMirzayanov for the great Codeforces and Polygon platforms.

You'll be given 5 problems, but this time you'll have 2 hours to solve them.

UPD: the scoring distribution will be 500-1000-1500-2000-2750.

UPD: the editorial.

UPD: congratulations to the winners:

Div.1:-

1. LJC00118
2. antontrygubO_o because he has to get a mention
3. Mehrdad_Sohrabi
4. zscoder
5. SSRS_

Div.2:-

1. __fishingprince__
2. Dolodu123
3. alya_wow
4. nxa_k_o
5. Kazaoka_Mari

Good luck & Have fun :D

Hi everyone!

Codeforces round #716 will take place on Apr/19/2021 16:35 (Moscow time). It's rated for the second division, but, as usual, first division participants can take part out of competition.

The problems are based on the Egyptian IOI qualification, and they were created by me and mahmoudbadawy. I'd like to thank:

• KAN and Nebuchadnezzar for their excellent coordination.
• antontrygubO_o for improving a problem, then rejecting all our problems without reading them, then testing the round.
• Yousef_Salama, Mohammad_Yasser, Noureldin, and Commando_ for testing the official contest.
• 74TrAkToR and psevdoinsaf for testing the round.
• MikeMirzayanov for the great codeforces and polygon platforms.

This may be the most and only balanced round I've ever set. You'll be given 5 problems and 2:15 hours to solve them.

UPD: the scoring distribution will be 500-1000-1500-2000-2500.

UPD: the editorial is out.

UPD: congratulations to the winners:

Div.1:-

1. neal
2. DreamingLeaf
3. Geothermal
4. cookiedoth
5. Tlatoani

Div.2:-

1. alya_wow
2. DatChelsea
3. Trump_Constructs_China
4. Dolodu123
5. Kazaoka_Mari

Good luck & Have fun :D

"Love" is a violent word.
"I love that about you..." Doesn't that just mean "If that changed, I wouldn't love you anymore?"
"Love" is a word that binds you.
— Touko Nanami —

Hi Codeforces!

Ari and I are pleased to invite you to participate in Codeforces Round #715 (Div. 1) and Codeforces Round #715 (Div. 2), which will be held at Apr/16/2021 17:35 (Moscow time). Each division will have 6 problems and 2 hours and 15 minutes to solve them.

Big thanks to the following people:

• Sir antontrygubO_o for being an amazing coordinator; the round wouldn't happen without you ❤️
• Scrubpai, 1-gon, hugopm, tfg, dorijanlendvaj, xuanquang1999, 300iq, Mike4235, Luminal, QuangBuiYT, jamienguyen, Pichu, chctxdy68, neko_nyaaaaaaaaaaaaaaaaa, gamegame, MrDecomposition, TheDramaQueen, nor, and alimq for testing the round and providing valuable feedback.
• MikeMirzayanov for the amazing platforms Codeforces and Polygon!
• And of course, to all the participants of this round!

The round will be themed around Yagate Kimi ni Naru, which is a romantic anime/manga series. If you haven't picked up the series yet, I highly recommend you to do so after the round ;)

Please do read all of the problems, stay hydrated during the round, and solve as many as you can! Good luck have fun to everyone!

Here are the scoring distributions:

• Div. 2: 500 — 1000 — 1500 — 2250 — 2500 — 3000
• Div. 1: 750 — 1000 — 1500 — 2250 — 2250 — 4000

UPD1: The round has concluded! Congratulations to the winners from both divisions:

• Div. 1:

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

• Div. 2:

1. wannahavealife (solved all problems!)
2. traxex2
3. _su1sen
4. I_love_Ilya_Krasnov
5. tsugu

UPD2: Editorial is up!

Thanks to everyone for participating in this contest, this has been a wild ride from start to finish. See you all next time!

Hello Codeforces!

On Apr/12/2021 17:35 (Moscow time) Educational Codeforces Round 107 (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 Roman Roms Glazov, 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:

Calling on all Codeforces,

Harbour.Space University is offering a unique opportunity to study in Barcelona for those who are interested in joining our young and dynamic competitive programming team. We accept medalists and top performers of IOI, IMO, ICPC, and participants with Codeforces rank above 2000.

Harbour.Space has a single, key requirement: be passionate and motivated to learn and/or work in the field of competitive programming in the long term. Even if you have already exhausted all your ICPC attempts, you are still welcome.

Join us to help build a comprehensive system of preparation for IOI and ICPC for the next generations! We believe that if you have the talent and determination to succeed, you can. We want to help you make it happen.

In addition to courses taught by some of the world's foremost experts in their fields, Harbour.Space offers these benefits upon acceptance for this scholarship:

• A full tuition fee waiver (Bachelor and Master degrees)
• Student visa
• Private health insurance
• Monthly living allowance*

In return, we demand dedication to learning and improving yourselves:

— Study three hours per day
— Train continuously for ICPC, if you are still eligible for participation
— Intern four hours per day

Ready to formally submit your application? Please register on our website, attach your latest CV, and pay a non-refundable €125 application fee. The fee guarantees we can process every single application in a fair and timely manner, and maintain the highest possible standards of assessment.

Our admission process is a holistic review of each candidate's abilities, achievements, and potential to create something exceptional.

You may choose to study in the following areas of specialization:

1. Computer Science
2. Data Science
3. Cyber Security
4. Front-End Development

All our degrees are taught in English. If you want to learn more about our programs please visit our website or contact our admissions office.

*The exact living allowance level throughout the entire duration of studies depends on the performance during the interview and on the overall performance. As a guidance, it is in the range of 500-1500 EUR.

Harbour.Space University Team

Congratulations to the winners:

145 successful hacks and 1221 unsuccessful hacks were made in total!

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

UPD: Editorial is out

The Programming Club, IIT Indore is proud to present our flagship event, Divide By Zero! The contest will take place on Apr/11/2021 17:35 (Moscow time). This round will be rated for all participants with a rating lower than 2100.

Thanks to the following people for making the round possible:

• KAN for coordinating throughout the round.
• kalpitk, ajit and 7dan for setting the problems.
• dvshah, bhanushali, sundesh, AniketSangwan, krishanu21saini, somyamehta_24 and hk2102 for their contribution to the problemset.
• Um_nik, dorijanlendvaj, chctxdy68, Osama_Alkhodairy, ScarletS, Discombobulated, kassutta and Jellyman102 for testing the problems.
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.

There are 6 problems, and 2 hours to solve them. The points distribution will be updated later.

Update: The scoring distribution is 500 -- 1250 -- 1500 -- 2000 -- 2750 -- 3000.

Update: Editorial is up.

PRIZES: Twenty Codeforces T-shirt will be given to:

• Top 10 Indian Participants
• Random 10 from top 100 (rank 11-100) Indian participants

Hope you guys enjoy the contest! See you on the leaderboard!

Update: Here is the list of winners who won T-shirts. We will contact you guys soon. Congrats!

Top 10 Indian Participants

• kshitij_sodani
• amnesiac_dusk
• jtnydv25
• pikel_rik
• JrNTR
• piyushsethia1999
• kesh4281
• scansex
• Lubba_Lubba
• Rahul

Random 10 from top 100 (rank 11-100) Indian participants

• not_an_alt
• Test2311
• rivalq
• teja349
• akulsareen
• maester
• ManavJ07
• iLLusio
• devansh05
• vok8

We have uploaded the link to the code for generating random numbers and ranklist here.

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #713 (Div. 3) will start at Apr/10/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended 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 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.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and sodafago.

Thanks Gassa, darkkcyan, bfs.07, Tzak, songsinger, Mukundan314, iankury, drunya, sodafago, ChOmPs, Programmer, Khairy, IITianUG, Rox for helping with testing the round!

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

</almost-copy-pasted-part>

Editorial: https://codeforces.com/blog/entry/89535

Hi Codeforces!

Yes, I know it's already April. Time flies so fast lately! Exactly a year ago we were just learning all the "delights" of lockdown.

So let's remember this 2020! What was it like? I don't know about you, but we had a hell of a lot of work.

I will now show you some graphs and you will be very surprised. Lockdown effect? Of course, but we did our best too.

Many thanks to everyone who did not stand aside! In 2020, we celebrated our 10th anniversary and crowdfunding money helps us grow and move forward. You helped us and each other. Thank you. Thank you for your contribution!

We've been working hard all year to make this community a better place. Did it work out? It's up to you to judge. Many thanks to everyone who invested time and effort:

• geranazavr555, kuviman, cannor147 helped a lot with development and new features;
• Una_Shem provided great organizational assistance;
• our problem coordinators are the greatest: KAN, antontrygubO_o, isaf27, 300iq, significant assistance was provided by BledDest, adedalic and Nebuchadnezzar, vovuh for preparing Div3 rounds;
• stingray advised and helped set up the network;
• our friends from VK for their help in our infrastructure;
• and help of problem writers and testers is immortal!

Time to take stock of 2020.

Partner Events

We are pleased to hold programming competitions with companies or for companies. I'm sure this is a great way to support the community of young programmers and hire talented candidates. Here is a list of our main partners this year:

• Telegram and personally Pavel Durov is supporting Codeforces activities for many years, every regular round is held with their help, thank you!
• ICPC — in 2020 we held several joint events (and we liked it!), I hope there will be more
• Mail.Ru — Technocup and Russian AI Cup
• VK, VK Cup — now a personal multi-track competition for Russian-speaking programmers
• XTX Markets, Codeforces Global Rounds — a series of 6 rounds with a separate scoring and souvenirs for the best participants
• Harbour.Space University — a series of educational rounds, the selection of summer school Tech Scouts
• JetBrains, Kotlin Heroes Rounds — Kotlin programming language contests
• Huawei — research competitions (marathons) with elements of machine learning
• Raiffeisenbank — round for both divisions with cool prizes
• Grakn Labs — round for both divisions with money prizes
• Microsoft, Microsoft Q # Coding Contest — unusual quantum computing competition