On Aug 23, at 12:00 UTC the ninth competition of the Eolymp Weekend Practice series will take place. Learn more on the competition website.

Format and Difficulty

Same as the first round, the competition is primarily aimed at improving practical skills. There will be 5 tasks of varying difficulty, the easiest of which can even be solved by beginners.

The scoring for each task being block-based (meaning points are awarded for each block of tests separately, and only if the solution passes all tests in the block). If there is a tie between two participants, the one whose last productive submission (i.e., a submission that added at least one point) was made earlier will be ranked higher in the leaderboard.

This series has a standard duration of two hours.

The statements will be available in the following languages: English, Ukrainian, Russian, Turkish, Spanish, Azerbaijani.

Registration

You can register for the competition on its page.

Thanks a lot to:

• Denisov for coordinating the contest
• Sergey Kolodyazhnyy for creating Eolymp
• waipoli, Denisov, barbie for authoring the problems
• Wansur, TimDee, Triseedot for testing the contest

Prizes

The top-10 participants of the competition, as well as 10 random participants from those who rank from 11th to 100th place, will receive prizes in the form of t-shirts. Please, note, that we have changed how prizes are awarded,

• We will send prizes for free to EU countries (with few exceptions), Ukraine and Azerbaijan. If you live in another country, we still may arrange delivery for you, but additional conditions and fees may apply.

• If you already got a T-Shirt in the first round, we will not send you another one, because it will be exactly the same.

Visit Frequently Asked Questions section to learn more.

Call for Tasks

We are looking for problem setters to help us prepare for the upcoming rounds. Learn more about how to submit problem.

Editorial is out

A

B The proof was wrong, now, the task is a bit changed. We are sorry for any inconvenience

C

D

E

Sponsors

This round is sponsored by Acai Travel

Acai Travel

Acai Travel is a seed-stage startup using AI to transform customer support in the travel industry. With $4M in funding and partnerships with leading global brands, our AI assistant integrates with travel and airline systems to deliver real-time information, automate ticket routing, analyze sentiment, and generate smart auto-replies—boosting efficiency and enhancing customer experiences.

We work with cutting-edge AI to solve real problems, not to chase trends. Our team, based in New York, Barcelona, and Pune, builds practical solutions rooted in strong values, curiosity, and a culture that fosters innovation and positive change.

Servus Codeforces,

I think many of you have already heard about stress testing, and many of you have your own scripts, etc., which may not always be convenient.
That’s why I present to you OHP, a convenient way to do stress testing.

Installation

wget https://github.com/waipoli/ohp/blob/master/ohp

However, I also recommend adding an alias to your bash/zsh/...rc afterwards.

Usage

To start, run ohp init in your working directory.

A folder will appear:

Put the correct solution in correct.cpp and the one you're testing in sol.cpp.

Write a generator using testlib in the gen.cpp file.

For the checker, you need to use three inputs/outputs like this:

#include "checker_utils.h"

using namespace std;

/*
int a, b, c;
input >> a;
output_correct >> b;
output_sol >> c;

return AC;
return WA;
*/
int main() {
    return 0;
}

If the checker finds the answer correct, return AC; otherwise, return WA.

Then run ohp compile and ohp run -t={number_of_tests}.

If it finds an incorrect test, it will display it to you, and you can find the test in the pipe folder.

Thats it)

If you have any questions or suggestions, feel free to write them in the comments or create pull requests on GitHub.

Hello, Codeforces!
In this blog, having thought of nothing better, I want to tell you a story.

A story about how little Chmyaaax, even before school, was forbidden to play computer games. About how, driven by a great desire to play tanks, he started making them in Scratch. About how he moved on from Scratch to Robot, and then to Turtle. From Turtle to Pascal. About how, at the age of 10, he was introduced to competitive programming. About how, after two failed Div3 contests, he quit for two years. About how, during that time, he passionately learned C++ so he could continue making computer games (which he still wasn’t allowed to play).

About how he later returned, motivated by money (the story about NEAR, where you had to reach 1600 to earn cash) (to then buy a second phone and play Brawl Stars). About how, after failing, he abandoned it again and went into commercial programming (making games). And then he came back to the sacred world, failing every TST the year before last.

After failing to qualify for EJOI and seeing his childhood friends surpass him, he gained something invaluable—motivation. But motivation alone wouldn’t take him far. Then, luck smiled upon him. He found a friend, a comrade. Someone who, just like him, had failed the EJOI TST with two rounds at zero points. He sat with him in voice calls for eight hours a day, grinding CF and USACO.

This is where the story of a boy ends and the story of success begins.

As if by magic, he qualified for every possible Olympiad in the 2023-2024 season. He realized that the ocean was much bigger than he had thought. He met many incredible people. After failing IOI (missing silver by just 3 points), he balanced that failure with a thin gold at BalkOI. He won gold at RMI. As part of the most sigma team(3_sigma_rule), he won the school ICPC.

He had achieved almost everything—everything except the one thing he had dreamed of since he first saw competitive programming. The GM title. And that’s where his second comrade came into play. Someone who, despite not knowing Generating Functions, managed to show their beauty to Chmyaksik. Thanks to this, in yesterday’s Div1, by taking the second derivative, he was able to simplify the formula and finally achieve the goal he had been working towards for six years.

To these two senpais, I want to once again express my deepest gratitude.
Thank you, barbie, for being with me <3, and thank you, Triseedot, for the Generating Functions and for the time we spent together <3. I hope you will also reach GM soon, and we will meet at the Olympiads this year!

Of course, I can’t forget my senseis:
Thank you, Nikolay Arzubov, Andriy_Popyk, Valentin Melnyk, and peltorator.
Thank you for your contests, lectures, and guidance.

And I hope this is only the beginning of his journey in this wonderful world.
Since I’d like to farm more contribution, I’d also like to (if anyone is interested) do an AMA session here (while I finally play CS).

Appologie for my bad memory, obviously my deepest gratitude to my the oldest, and my the most wise senpai TimDee, who has shown me a Little Company.

Thank you for reading this blog.

Eolymp Cup #4

Get ready for the final round of the Eolymp Cup happening on Sunday, March 2! Compete for a chance to win free HSU scholarships, Eolymp subscriptions, and our exclusive T-Shirts. Don’t miss out on the action—we’re excited to see you there!

About

Eolymp Cup is a programming competition for students. The competition consists of 4 rounds, held throughout the year. Each round features 6 problems, each designed to challenge participants' knowledge of algorithms, data structures and programming.

The competition is open to everyone, but prizes will only be awarded to participants who are born after January 1, 2002. All other participants will compete unofficially.

Format and Duration

In each round, you are given 3 hours to solve 6 problems. Each problem is split into sub-tasks, which represent part of the problem. The points are awarded by sub-task, meaning you have to solve an entire sub-task to get points.

Registration

You can register on the contest page, just click "Join" on the top of the page.

Thanks a lot to:

• Denisov for coordinating the contest

• Sergey Kolodyazhnyy for creating Eolymp

• barbie, I_love_klymso, Denisov, waipoli for authoring the problems

• TimDee, Wansur, Triseedot, Ignut, 160cm, xGaz_, tedi_2.0, FBI, JuicyGrape, Pa_sha for testing the contest

Call for Problem Setters

Even though this is the final round of Eolymp Cup we are still looking for problem setters for our Weekend Practice competition series. If you're interested, please email us at hello@eolymp.com. Problem setters will be compensated and receive exclusive merch and other perks.

Prizes

The winners of the competition, based on the results of all rounds, will receive a trophy, medals and valuable prizes.

• 1st prize: The absolute winner will receive the Eolymp Cup trophy, first-place medal and Apple MacBook Air 13".

• 2nd prize: The participant ranked second will receive the first-place medal and an Apple iPad Air 11" tablet computer.

• 3rd prize: The participants ranked 3-6 will receive second-place medals and an Apple Watch SE smartwatch.

• 4th prize: Participants ranked 7-12 will receive third-place medals and Keychron K8 Wireless keyboard.

Additionally, the top-12 participants and 25 randomly selected participants in top-250 will receive exclusive T-Shirts and stickers.

Get scholarship at Harbour.Space University

Harbour.Space University is a private international university focused on Technology, Business and Design with campuses in Barcelona (Spain) and Bangkok (Thailand). HSU places a strong emphasis on its connection to the tech industry and works closely with industry experts across the world to immerse students in a dynamic, multi-cultural ecosystem of education, professional experience, and networking with like-minded peers and actively practicing professionals. In April 2024, Harbour.Space University won the Gold Medal in ICPC World Final, outcompeting such universities as MIT, Stanford, Oxford, Cambridge, among others.

Scholarship

In each round, the Top-3 participants as well as 2 randomly selected participants among the Top-50 will receive a full scholarship at Harbor.Space University, which includes:

• Full Tuition Fee Coverage: EUR 19,900 for Bachelor's programs or EUR 22,900 for Master's programs

• Program Choice: all programs of HSU across tech, business, and design are in scope

• Campus Choice: choose to study in one of HSU’s campuses in two vibrant cities, in Barcelona or Bangkok

• Internship opportunities: you will also be offered to join Talent Pool of Harbour.Space University and be considered for paid internship opportunities from university’s industry partners

Important

If you're interested in receiving a scholarship, please be sure to mark "Apply for scholarship at Harbor.Space University" during registration.

Free 3-week course

All competition participants will also have an exclusive opportunity to register for a Raffle. The 5 lucky winners will receive a free 3-week course of their choice at HSU, see schedule.

Register for a Ruffle

Win free Eolymp subscriptions

Based on the results, we will create an additional rating among educational institutions. After each round, the top 10 institutions as well as 10 randomly selected institutions among these who scored at least 100 points, will be awarded a coupon for Eolymp Competition Platform. The coupon will give a 100% discount for Advanced plan for the first 6 months with up to 100 seats.

The students should specify a university or a school they are representing during the registration process. Despite its name, the ranking includes all educational institutions: universities, schools, colleges etc. The institutions are ranked based on the total number of points scored by their students.

Pinely

This round is sponsored by Pinely.

Pinely is a dynamic algorithmic trading firm, privately owned & funded, with a presence in Singapore, the Netherlands, and Cyprus. We specialize in high-frequency and ultra-low latency trading, striving to be among the top trading companies worldwide.

Our team tackles everyday challenges like developing trading strategies, optimizing systems for minimal latency, saving and processing large volumes of historical data.

Our flat structure and collaborative environment make everyone feel heard and cultivate a culture fueled by ideas and a love for innovation.

We are a team of mathematicians, programmers, engineers, and computer scientists, united by a passion for knowledge. Our work demands exceptional C++ coding, algorithmic thinking, and mathematical intuition, attracting top talent, including winners and awardees of such respective challenges as ICPC, IMC, HITB PRO CTF, Google HashCode, etc.

To join our team, please send your CV to hr@pinely.com.

Visit pinely.com

The original Eolymp blog could be found here.

Eolymp Cup #3

Get ready for the third round of the Eolymp Cup happening on Sunday, December 15! Compete for a chance to win free HSU scholarships, Eolymp subscriptions, and our exclusive Evil Chmyaaax T-Shirt. Don’t miss out on the action—we’re excited to see you there!

About

Eolymp Cup is a programming competition for students. The competition consists of 4 rounds, held throughout the year. Each round features 6 problems, each designed to challenge participants' knowledge of algorithms, data structures and programming.

The competition is open to everyone, but prizes will only be awarded to participants who are born after January 1, 2002. All other participants will compete unofficially.

Format and Duration

In each round, you are given 3.5 hours to solve 6 problems. Each problem is split into sub-tasks, which represent part of the problem. The points are awarded by sub-task, meaning you have to solve an entire sub-task to get points.

Registration

You can register on the contest page, just click "Join" on the top of the page.

Thanks a lot to:

• Denisov for coordinating the contest

• Sergey Kolodyazhnyy for creating Eolymp

• waipoli, barbie, Denisov, BalashovIvan for authoring the problems

• peltorator, TimDee, Triseedot, Ignut, FBI, JuicyGrape, Pa_sha for testing the contest

Prizes

The winners of the competition, based on the results of all rounds, will receive a trophy, medals and valuable prizes.

• 1st prize: The absolute winner will receive the Eolymp Cup trophy, first-place medal and Apple MacBook Air 13".

• 2nd prize: The participant ranked second will receive the first-place medal and an Apple iPad Air 11" tablet computer.

• 3rd prize: The participants ranked 3-6 will receive second-place medals and an Apple Watch SE smartwatch.

• 4th prize: Participants ranked 7-12 will receive third-place medals and Keychron K8 Wireless keyboard.

Additionally, the top-12 participants and 25 randomly selected participants in top-250 will receive exclusive T-Shirts and stickers.

Get scholarship at Harbour.Space University

Harbour.Space University is a private international university focused on Technology, Business and Design with campuses in Barcelona (Spain) and Bangkok (Thailand). HSU places a strong emphasis on its connection to the tech industry and works closely with industry experts across the world to immerse students in a dynamic, multi-cultural ecosystem of education, professional experience, and networking with like-minded peers and actively practicing professionals. In April 2024, Harbour.Space University won the Gold Medal in ICPC World Final, outcompeting such universities as MIT, Stanford, Oxford, Cambridge, among others.

Scholarship

In each round, the Top-3 participants as well as 2 randomly selected participants among the Top-50 will receive a full scholarship at Harbor.Space University, which includes:

• Full Tuition Fee Coverage: EUR 19,900 for Bachelor's programs or EUR 22,900 for Master's programs

• Program Choice: all programs of HSU across tech, business, and design are in scope

• Campus Choice: choose to study in one of HSU’s campuses in two vibrant cities, in Barcelona or Bangkok

• Internship opportunities: you will also be offered to join Talent Pool of Harbour.Space University and be considered for paid internship opportunities from university’s industry partners

Important

If you're interested in receiving a scholarship, please be sure to mark "Apply for scholarship at Harbor.Space University" during registration.

Free 3-week course

All competition participants will also have an exclusive opportunity to register for a Raffle. The 5 lucky winners will receive a free 3-week course of their choice at HSU, see schedule.

Register for a Ruffle

Win free Eolymp subscriptions

Based on the results, we will create an additional rating among educational institutions. After each round, the top 10 institutions as well as 10 randomly selected institutions among these who scored at least 100 points, will be awarded a coupon for Eolymp Competition Platform. The coupon will give a 100% discount for Advanced plan for the first 6 months with up to 100 seats.

The students should specify a university or a school they are representing during the registration process. Despite its name, the ranking includes all educational institutions: universities, schools, colleges etc. The institutions are ranked based on the total number of points scored by their students.

Pinely

This round is sponsored by Pinely.

Pinely is a dynamic algorithmic trading firm, privately owned & funded, with a presence in Singapore, the Netherlands, and Cyprus. We specialize in high-frequency and ultra-low latency trading, striving to be among the top trading companies worldwide.

Our team tackles everyday challenges like developing trading strategies, optimizing systems for minimal latency, saving and processing large volumes of historical data.

Our flat structure and collaborative environment make everyone feel heard and cultivate a culture fueled by ideas and a love for innovation.

We are a team of mathematicians, programmers, engineers, and computer scientists, united by a passion for knowledge. Our work demands exceptional C++ coding, algorithmic thinking, and mathematical intuition, attracting top talent, including winners and awardees of such respective challenges as ICPC, IMC, HITB PRO CTF, Google HashCode, etc.

To join our team, please send your CV to hr@pinely.com.

Visit pinely.com

The original Eolymp blog could be found here.

Eolymp Cup #2

We are very excited to announce the second round of Eolymp Cup on 6th of October at 15.00 UTC! Take up a challenge to get a chance to win a trophy, medals, prizes, and scholarships at Harbour.Space University.

Eolymp Cup is a programming competition for students. The competition consists of 4 rounds, held throughout the year. Each round features 6 problems, each designed to challenge participants' knowledge of algorithms, data structures and programming.

The competition is open to everyone, but prizes will only be awarded to participants who are born after January 1, 2002. All other participants will compete unofficially.

Registration

You can register on the contest page, just click "Join" on the top of the page.

Format and Duration

In each round, you are given 3 hours to solve 6 problems. Each problem is split into sub-tasks, which represent part of the problem. The points are awarded by sub-task, meaning you have to solve an entire sub-task to get points.

Thanks a lot to:

• Denisov and arsijo for coordinating the contest

• Sergey Kolodyazhnyy for creating Eolymp

• waipoli, barbie, Triseedot, Denisov for authoring the problems

• peltorator, Frus, xGaz_, nika-skybytska, TimDee, Wansur, Ignut, cherryk, FBI, ksu_, JuicyGrape, Pa_sha for testing the contest

Prizes

The winners of the competition, based on the results of all rounds, will receive a trophy, medals and valuable prizes.

• 1st prize: The absolute winner will receive the Eolymp Cup trophy, first-place medal and Apple MacBook Air 13".

• 2nd prize: The participant ranked second will receive the first-place medal and an Apple iPad Air 11" tablet computer.

• 3rd prize: The participants ranked 3-6 will receive second-place medals and an Apple Watch SE smartwatch.

• 4th prize: Participants ranked 7-12 will receive third-place medals and Keychron K8 Wireless keyboard.

Additionally, the top-12 participants and 25 randomly selected participants in top-250 will receive exclusive T-Shirts and stickers.

Get scholarship at Harbour.Space University

Harbour.Space University is a private international university focused on Technology, Business and Design with campuses in Barcelona (Spain) and Bangkok (Thailand). HSU places a strong emphasis on its connection to the tech industry and works closely with industry experts across the world to immerse students in a dynamic, multi-cultural ecosystem of education, professional experience, and networking with like-minded peers and actively practicing professionals. In April 2024, Harbour.Space University won the Gold Medal in ICPC World Final, outcompeting such universities as MIT, Stanford, Oxford, Cambridge, among others.

Scholarship

In each round, the Top-3 participants as well as 2 randomly selected participants among the Top-50 will receive a full scholarship at Harbor.Space University, which includes:

• Full Tuition Fee Coverage: EUR 19,900 for Bachelor's programs or EUR 22,900 for Master's programs

• Program Choice: all programs of HSU across tech, business, and design are in scope

• Campus Choice: choose to study in one of HSU’s campuses in two vibrant cities, in Barcelona or Bangkok

• Internship opportunities: you will also be offered to join Talent Pool of Harbour.Space University and be considered for paid internship opportunities from university’s industry partners

Important

If you're interested in receiving a scholarship, please be sure to mark "Apply for scholarship at Harbor.Space University" during registration.

Free 3-week course

All competition participants will also have an exclusive opportunity to register for a Raffle. The 5 lucky winners will receive a free 3-week course of their choice at HSU, see schedule.

Register for a Ruffle

Win free Eolymp subscriptions

Based on the results, we will create an additional rating among educational institutions. After each round, the top 10 institutions as well as 10 randomly selected institutions among these who scored at least 100 points, will be awarded a coupon for Eolymp Competition Platform. The coupon will give a 100% discount for Advanced plan for the first 6 months with up to 100 seats.

The students should specify a university or a school they are representing during the registration process. Despite its name, the ranking includes all educational institutions: universities, schools, colleges etc. The institutions are ranked based on the total number of points scored by their students.

Pinely

This round is sponsored by Pinely.

Pinely is a dynamic algorithmic trading firm, privately owned & funded, with a presence in Singapore, the Netherlands, and Cyprus. We specialize in high-frequency and ultra-low latency trading, striving to be among the top trading companies worldwide.

Our team tackles everyday challenges like developing trading strategies, optimizing systems for minimal latency, saving and processing large volumes of historical data.

Our flat structure and collaborative environment make everyone feel heard and cultivate a culture fueled by ideas and a love for innovation.

We are a team of mathematicians, programmers, engineers, and computer scientists, united by a passion for knowledge. Our work demands exceptional C++ coding, algorithmic thinking, and mathematical intuition, attracting top talent, including winners and awardees of such respective challenges as ICPC, IMC, HITB PRO CTF, Google HashCode, etc.

To join our team, please send your CV to hr@pinely.com.

Visit pinely.com

The original Eolymp blog could be found here.

UPD: The editorial is published, you can reach it by following this link:

• Annihilator Gun

• Link-Cut Dumplings

• Finally a Problem Without a Legend

• Traditional Game

• Coloring Geysers

• Beauty Permutation Queries — will be posted soon

Eolymp Cup #1

We are very excited to announce our new competition! Join us at Eolymp Cup, a programming competition for students from everywhere! Take up a challenge to get a chance to win a trophy, medals, prizes, and scholarships at Harbour.Space University.

Eolymp Cup is a programming competition for students. The competition consists of 4 rounds, held throughout the year. Each round features 6 problems, each designed to challenge participants' knowledge of algorithms, data structures and programming.

The competition is open to everyone and will be held on Saturday, July 6, 2024 at 17:00 UTC+2. Still, prizes will only be awarded to participants who are currently enrolled in a university or school and born after January 1, 2002. All other participants will compete unofficially.

Registration

You can register on the contest page, just click "Join" on the top of the page.

Format and Duration

In each round, you are given 3 hours to solve 6 problems. Each problem is split into sub-tasks, which represent part of the problem. The points are awarded by sub-task, meaning you have to solve an entire sub-task to get points.

Prizes

The winners of the competition, based on the results of all rounds, will receive a trophy, medals and valuable prizes.

• 1st prize: The absolute winner will receive the Eolymp Cup trophy, first-place medal and Apple MacBook Air 13".

• 2nd prize: The participant ranked second will receive the first-place medal and an Apple iPad Air 11" tablet computer.

• 3rd prize: The participants ranked 3-6 will receive second-place medals and an Apple Watch SE smartwatch.

• 4th prize: Participants ranked 7-12 will receive third-place medals and Keychron K8 Wireless keyboard.

Additionally, the top-12 participants and 25 randomly selected participants in top-250 will receive exclusive T-Shirts and stickers.

Get scholarship at Harbour.Space University

Harbour.Space University is a private international university focused on Technology, Business and Design with campuses in Barcelona (Spain) and Bangkok (Thailand). HSU places a strong emphasis on its connection to the tech industry and works closely with industry experts across the world to immerse students in a dynamic, multi-cultural ecosystem of education, professional experience, and networking with like-minded peers and actively practicing professionals. In April 2024, Harbour.Space University won the Gold Medal in ICPC World Final, outcompeting such universities as MIT, Stanford, Oxford, Cambridge, among others.

Scholarship

In each round, the Top-3 participants as well as 2 randomly selected participants among the Top-50 will receive a full scholarship at Harbor.Space University, which includes:

• Full Tuition Fee Coverage: EUR 19,900 for Bachelor's programs or EUR 22,900 for Master's programs

• Program Choice: all programs of HSU across tech, business, and design are in scope

• Campus Choice: choose to study in one of HSU’s campuses in two vibrant cities, in Barcelona or Bangkok

• Internship opportunities: you will also be offered to join Talent Pool of Harbour.Space University and be considered for paid internship opportunities from university’s industry partners

Important

If you're interested in receiving a scholarship, please be sure to mark "Apply for scholarship at Harbor.Space University" during registration.

Free 3-week course

All competition participants will also have an exclusive opportunity to register for a Raffle. The 5 lucky winners will receive a free 3-week course of their choice at HSU, see schedule.

Register for a Ruffle

Win free Eolymp subscriptions

Based on the results, we will create an additional rating among educational institutions. After each round, the top 10 institutions as well as 10 randomly selected institutions among these who scored at least 100 points, will be awarded a coupon for Eolymp Competition Platform. The coupon will give a 100% discount for Advanced plan for the first 6 months with up to 100 seats.

The students should specify a university or a school they are representing during the registration process. Despite its name, the ranking includes all educational institutions: universities, schools, colleges etc. The institutions are ranked based on the total number of points scored by their students.

The original Eolymp blog could be found here.

UPD: The editorial is published, you can reach it by following this link:

• Pref Suff Chmyaaax Diff

• Warm-up Equation

• The Queue

• Infinity Tree

• Anton's Vyshyvanka

• Mirror Tree?

This is the original results blog on Eolymp.

From 10th to 16th May, Ukrainian Selection Camp for the IOI (International Olympiad in Informatics), BOI (Balkan Olympiad in Informatics) was held in Wrocław, Poland.

Thanks to University of Wrocław and gawry for the second time for help in organising the selections!

We are very grateful to Sergey Kolodyazhnyy for creating powerful online judge Eolymp.

Also, I would like to thank oleh1421 and kostia244 for preparing amazing problems. Maryna, Ilona and Melissa_14 for looking after the participants and Federation of Olympic Programming of Ukraine presented by arsijo for coordinating the entire process.

So, on IOI Ukrainian Team will be represented by:

• Andrii Smutchak(xGaz_) — 2nd time at IOI(IOI 23 Silver), 0 attempts left
• Ihnat Zharikhin(Ignut) — 1st time at IOI, 0 attempts left
• Denys Tereshchenko(TheQuantiX) — 1st time at IOI, 0 attempts left
• Illia Permiakov(160cm) — 1st time at IOI, 0 attempts left

Left to right: Illia, Ihnat, Andrii, Denys

And on BOI Ukrainian Team will be represented by:

• Maksym Shvedchenko(Umanity) — 1st time at BOI, 1 attempt left
• Valerii Kovnatskyi(Triseedot) — 1st time at BOI, 0 attempts left
• Daria Perekopska(cherryk) — 1st time at BOI, 1 attempt left
• Kyrylo Redenskyi(Relex) — 1st time at BOI, 0 attempts left

Left to right: Maksym, Valerii, Daria, Kyrylo

As usual some photos of our delegation included =)

Good luck to them at the upcoming olympiads!

On May 19, at 16:00 UTC the second competition of the Eolymp Weekend Practice series will take place. Learn more on the competition website.

Format and Difficulty

Same as the first round, the competition is primarily aimed at improving practical skills. There will be 5 tasks of varying difficulty, the easiest of which can even be solved by beginners.

The scoring for each task being block-based (meaning points are awarded for each block of tests separately, and only if the solution passes all tests in the block). If there is a tie between two participants, the one whose last productive submission (i.e., a submission that added at least one point) was made earlier will be ranked higher in the leaderboard.

This series has a standard duration of two hours.

The statements will be available in the following languages: English, Ukrainian, Russian, Polish, German, French, Spanish, Azerbaijani.

Registration

You can register for the competition on its page.

Thanks a lot to:

• arsijo for coordinating the contest
• Sergey Kolodyazhnyy for creating Eolymp
• Umanity, barbie, Frus for authoring the problems
• peltorator, 160cm, TheQuantiX, Ignut, Geforgs, fatonims, Melissa_14 for testing the contest

Prizes

The top-10 participants of the competition, as well as 10 random participants from those who rank from 11th to 100th place, will receive prizes in the form of t-shirts. Please, note, that we have changed how prizes are awarded,

• We will send prizes for free to EU countries (with few exceptions), Ukraine and Azerbaijan. If you live in another country, we still may arrange delivery for you, but additional conditions and fees may apply.

• If you already got a T-Shirt in the first round, we will not send you another one, because it will be excatly the same.

Visit Frequently Asked Questions section to learn more.

UPD:

Congrats to the winners:

• VladProg
• wakaka
• Triseedot
• nfssdq
• andr1y
• Psiuk_Yurii
• xGaz_
• Valera_Grinenko
• Tahirliyev
• Wansur

Next Sunday, March 24, at 16:00 UTC the first competition of the Eolymp Weekend Practice series will take place.

Format and Difficulty

As the name suggests, this series of competitions is primarily aimed at improving practical skills. There will be 5 tasks of varying difficulty, the easiest of which can even be solved by beginners.

The distribution of points by tasks is 50-100-200-300-350, with scoring for each task being block-based (meaning points are awarded for each block of tests separately, and only if the solution passes all tests in the block). If there is a tie between two participants, the one whose last productive submission (i.e., a submission that added at least one point) was made earlier will be ranked higher in the leaderboard.

This series has a standard duration of two hours.

The statements will be available in the following languages: English, Ukrainian, Russian, Polish, German, French, Spanish, Azerbaijani.

Registration

You can register for the competition on its page.

Prizes

The top-10 participants of the competition, as well as 10 random participants from those who rank from 11th to 100th place, will receive prizes in the form of t-shirts. Please note that Eolymp currently sends prizes only to countries that are part of the Council of Europe.

Read more

UPD:

Congrats to the winners!:

1. andrey27sm

2. NK_

3. TheQuantiX

4. MAKMED1337

5. esomer

6. thenymphsofdelphi

7. huz_n

8. fuad27

9. Glauco

10. Sahib_

The editorial is available by the following links:

1. The Cubes
2. The Strings
3. Some Complex Formulas
4. Scared String!
5. Is This FFT?

Hello codeforces!

Recently in the problem I came across with this data structure, which can perform this operations:

• add element

• delete element

• return the maximal of it

with O(1) for query.

So the question is simple: is it exist?

Given an array of integers a (len(a) < 10^5, 1 <= a[i] <= 10^9).

There are q queries of two types:

In the first type, two numbers x (0 <= x < len(a)) and y (1 <= y <= 10^9) are given. You need to change the element of the array a at position x to y.

In the second type, two numbers l and r are given (0 <= l < len(a), 0 <= r < len(a), l < r). You need to find two different indices x1 and x2 belonging to the segment from l to r (inclusive) such that their greatest common divisor (GCD) is the largest possible among all pairs (output the GCD).

I know how to solve this problem with brute force O(qn^2), but I am personally interested in finding a solution with a better complexity (O(qlog(N))).