Hello again, Codeforces!

I am glad to invite you to Codeforces Round 580, which will take place on Aug/18/2019 16:45 (Moscow time). Round will be rated for both divisions.

All problems in this round were created and prepared by me, antontrygubO_o. I tried to make them interesting and hope that you will enjoy them!

A lot of thanks to arsijo for the excellent coordination of the round, kefaa2, gepardo, danya.smelskiy, re_eVVorld, Xellos, GandalfTheGrey, prof.PVH, KAN for the testing and valuable comments, and to Mike MikeMirzayanov Mirzayanov for the amazing platforms Codeforces и Polygon.

Participants in each division will be offered 6 problems and 2 hours 10 minutes to solve them. As usual, I strongly recommend reading statements of all problems!

I wish you good luck and high rating!

UPD1:

Scoring distribution of Div $$$2$$$ round: 500 — 1000 — 1500 — 1750 — 2250 — 3000

Scoring distribution of Div $$$1$$$ round: 500 — 750 — 1250 — 2000 — 2500 — 3000

UPD2:Editorial

UPD3 Congrats to winners!

Div 1:

1. TLE

2. Um_nik

3. mnbvmar

4. Benq

5. CauchySheep

Div 2:

1. kkkkk11

2. sucuk

3. ujrepacul

4. zzffxx

5. Illicit

Hello!

We are very pleased to cooperate with XTX Markets, thanks to whom we are able to hold the Global rounds. Four of the six of them are already passed and here are the current results.

In short, XTX Markets is a leading quantitative-driven electronic market maker Launched in 2015, XTX Markets has rapidly become the number 1 FX spot liquidity provider by volumes globally, surging ahead of global banks.

Thanks for supporting our community!

We are happy to announce that XTX recently launched the XTX Markets Global Forecasting Challenge, powered by Correlation One.

The XTX Markets Global Forecasting Challenge is an online competition for aspiring quantitative professionals, where contestants are tasked to develop a predictive model based on training data provided by XTX.

Competition highlights include:

• Over $100,000 in total cash prizes.
• $7,500 for the best submission from a participant aged under-25 (as of 1st July 2019).
• Exciting job opportunities in London.
• Opportunity to compete against the best quantitative minds from around the world.

The competition is open to all data-minded contestants from 1st of July to 30th of September, 2019.

To get started, please sign up below.

We hope you'd be interested!

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Hello! Codeforces Round #579 (Div. 3) will start at Aug/13/2019 17:35 (Moscow time). You will be offered 6 or 7 problems (or 8) 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 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. 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 6 or 7 (or 8) 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 a 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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of my work. Thanks to my good friends Mikhail PikMike Piklyaev, Maksim Ne0n25 Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

I also would like to say that participants who will submit wrong solutions on purpose and hack them afterwards (example) will not be shown in the hacking leaders table.

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UPD: Editorial is published!

안녕하세요, 코드포스! (Hello, Codeforces!)

We're glad to introduce you to Codeforces Round #578 (Div. 2), which will start at Aug/11/2019 15:35 (Moscow time). The round is rated for Div. 2 participants.

You will be given 6 problems and 2 hours to solve them. The score distribution will be announced later.

The problems are prepared by hyunuk and me.

Thanks to pllk, Learner99, Rox, mohammedehab2002, cheetose, jh05013, rkm0959, edenooo, and alex9801 for testing the round. We would also like to specially thank to KAN and arsijo for coordinating the round, and of course, MikeMirzayanov for Codeforces and Polygon platform.

This is our very first round, so I hope you enjoy it a lot!

UPD: The scoring distribution is 500 — 1000 — 1250 — 2000 — 2000 — 2500

UPD2: The contest is finished. Thanks for joining us! Here's the editorial.

UPD3: Congratulations to the winners!

Div. 2

1: gamegamewillwinioi2020

2: oliviahye

3: ccf_n0i

4: 2om_neek

5: Tropical_maid

Unofficial Div. 1

1: kcm1700

2: uwi

3: square1001

4: kmjp

5: KrK

Dear friends!

We're thrilled to invite you to the two great events which will be held in Turkey for the first time ever!

ICPC is delighted to announce the First National Programming Contest in Turkey, organized by inzva in collaboration with the Middle East Technical University (METU) to be held on September 13-15, 2019.

We’re inviting university teams across Turkey to participate in the national contest in Beykoz Kundura, Istanbul — completely free of charge — thanks to the ICPC local partner — inzva, a non-profit community focused on artificial intelligence and algorithm, supported by BEV — an Education Foundation for the Digital Native Generation.

Top ten teams qualifying in this contest can then participate in the Southerneastern Europe Regional Contest, and will be financially supported for this purpose. The winner teams of the Southern Europe Regional Contest are eligible to participate at the ICPC Moscow 2020 World Finals!

Also, this weekend on September 14 in Istanbul will be held the Annual ICPC Alumni Reunion Dinner.

It is the first ICPC Alumni event happening in Southeastern European Region, and we will be extremely honored to welcome you and your colleagues/classmates/coaches on this special day. Please feel free to extend this invitation to your guests.

ICPC Alumni Reunion Dinner will be held on Saturday, September 14, 2019, at Beykoz Shoe Factory, Yaliköy Mah. Süreyya İlmen Cad. No:1/1 Beykoz, Istanbul. There will be a reception that begins at 4pm, with dinner to follow at 5pm. Please feel free to extend this invitation to your guests.

This event is free of charge but requires reservation before September 1, 2019. Please be sure to RSVP via this form to secure your place:

In addition to this being a fun reunion for local ICPC participants, we will be recognizing the accomplishments of various ICPC volunteers who make the show happen each year. ICPC Executive Director Bill Poucher will be in attendance, and various other judges, staff, and coaches. We would be honored if you can make it as well, and partake in the festivities.

We are unfortunately unable to welcome all outside guests but have done our best to invite as many ICPC Alumni as possible, please feel free to extend this invitation to any other finalists/regional participants that you know to be in the area. You can also send their names and contact info to manager@icpc.global so that we can add them to the invitation list. Once registered — you’ll receive official confirmation of your personal invitation, as well as all travel details.

Looking forward to meeting you in Turkey!

Hello Codeforces!

On Aug/07/2019 17:35 (Moscow time) Educational Codeforces Round 70 (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 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 Ne0n25 Mescheryakov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all participants!

UPD: Our friends at Harbour.Space also have a message for you:

Hello Codeforces!

Ready to get deep?

Take a minute and ask yourselves — what skills are I missing, that I would love to have? What are those key qualities that would take me from being a decent developer to an extraordinary one? Am I where I want to be, in terms of personal progress?

At Harbour.Space, we focus on the key technical and social requirements of the jobs of the future. Our three-week courses are designed for students to acquire and develop specific skills through seminars, workshops, projects, and case studies in a very short amount of time.

Mike Mirzayanov’s course, Advanced Algorithms and Data Structures, is a great example of this:

This, in combination with our unique academic environment, extensive professional network, and our seaside campus in the beautiful city of Barcelona, provides for a truly unique learning experience.

Interested?

Fill out the form below, get more information, and see how you can come attend Mike’s course to see what all the fuss is about!

See you soon!

Harbour.Space

Congratulations to the winners:

109 successful hacks and 290 unsuccessful hacks were made in total!

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

UPD: Editorial is out

Hello, Codeforces!

I am glad to invite you to take part in Codeforces Round #577 (Div 2), which will be held on Sunday, 4 August at 16:35 UTC.

You will be given 5 problems, one of them will have 2 subtasks and 2 hours to solve them.

The round will be rated for the second division.

Huge thanks to _kun_ and KAN for helping to prepare the round.

I would like to thank to 300iq, isaf27, V--gLaSsH0ldEr593--V, pllk, mohammedehab2002, tractor74.ru, Rox, opukittpceno_hhr for testing the round.

And thanks to MikeMirzayanov for the great codeforces and polygon platforms.

This is my first Codeforces round. Hope you will enjoy it.

Good luck and have fun!

UPD: The scoring distribution is: 500 — 1000 — 1500 — 2000 — (2000 + 1000)

UPD2: Editorial

UPD3: Congratulations to the winners:

Div2:

1: wwaynetuu

2: jerome_mei

3: satu0king

4: Yazmau

5: Tlatoani, 2-SAD, boba5551

Unofficial Div1:

1: neal

2: uwi

3: scott_wu

4: I_love_Tanya_Romanova

5: ecnerwala

Hello!

I'm glad to invite you all to Round 576 which will take place on Jul/30/2019 17:35 (Moscow time).

There will be 6 problem in both divisions.

Round is based on Team Olympiad in Computer Science Summer School. It is (yet another) summer school for schoolchildren organized by Higher School of Economics and "Strategy" Center in Lipetsk. Almost all the problems are authored and prepared by teachers and teaching assistants in CSSS: Um_nik, Burunduk1, I_love_fake123, MakArtKar, Villen3tenmerth, Aphanasiy, Gadget. One of the problems is authored by Merkurev (just because we are friends :) ). One more problem for the round was added by KAN.

I would like to thank KAN for CF round coordination, I_love_Tanya_Romanova, Merkurev, Rox and tractor74.ru for testing, and Codeforces and Polygon team for these beautiful platforms.

Scoring will be announced.

Upd: We added one more problem to div.1 contest, now both contests have 6 problems (4 in common). The round is not combined, if it were, I would write "combined" in the title.

Scoring distribution:
div2: 500-750-1250-1750-2500-3000
div1: 500-750-1250-1500-1750-2250

Congratulations to our winners!
div.1:
1. Radewoosh
2. tourist
3. mnbvmar
4. Benq
5. pashka
div.2:
1. ChthollyNotaSeniorious
2. Honour_34
3. ldxcaicai
4. shogunator
5. Yatsumura

Editorial won't be published.

The 26th Central European Olympiad in Informatics will take place in Bratislava, Slovakia, during July 23rd-29th 2019. The most gifted high school students from 13 countries will have the opportunity to prove their knowledge and skills in informatics.

Codeforces will organise the online mirror for this year's competition. The online mirrors will take place after the finish of each of the 2 competition days, having the same scoring format.

The online mirror schedules are the following:

• Jul/25/2019 17:05 (Moscow time)
• Jul/28/2019 11:05 (Moscow time)

Contest format

• The contest will be unrated for all users.
• You will have to solve 3 tasks in 5 hours.
• There will be full feedback throughout the entire contest.
• The scoreboard will be hidden until the end of the contest.
• The tasks will have partial scoring. The maximum score for each problem will be 100 points.
• Among multiple submissions only the one that achieves the maximum score is counted towards the final ranking.
• The submission time does not matter for ranking.
• There will be enough fun for all colours ranging from newbie to international grandmaster. Legendary grandmasters can spice it up by turning it into a drinking game (ask Radewoosh for details).

Link to onsite contest with official rules and scoreboard

UPDATE: Much nicer scoreboard than on the first day made by arsijo. Many thanks!

Congratulations to all onsite contestants who battled our unusually hard problemset for 10 hours. You can view the final standings.

Many thanks to KAN for running the mirror, MikeMirzayanov for both platforms, all of our authors, testers and the whole CEOI staff and sponsors!

Day 1 mirror:

1. mnbvmar 300
2. Benq 300
3. gamegame 281
4. ainta 271
5. __.__ 254

Day 2 mirror:

1. zx2003 230
2. saba2000 230
3. TLE 200
4. cuizhuyefei 200
5. panole 200
6. dacin21 200

Results of both days combined: (https://codeforces.com/spectator/ranklist/e354b9b95c3626a3cfdfdb9eb37a7a6f)

Editorials: day1 day2