Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #28 will take place on Wednesday, May/10/2017 13:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1650. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

• 1 random prize for the top 20%
• 1 random prize for the next 30%
• 1 random prize for the bottom 50%

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Platform changes

• CS Academy is now a single page application.
• New activity section below the global chat
• Division cutoff changed to 1650

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

CS Academy will continue to host the online mirror of Romania's IOI 2017 Selection Contests. The third round will take place on Wednesday, 10/May/2015 07:00:00 (UTC). The round will be rated for all users. You will have to solve 3 problems in 5 hours. The statements will be available in English and Romanian.

Contest format:

• You will have to solve 3 tasks in 5 hours.
• There will be full feedback throughout the entire contest.
• The tasks will have partial scoring. The maximum score for each problem will be 100 points.
• There will be no tie breaker, so two users having the same total score at the end of the contest will share the same place in the standings.

If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

CS Academy will host the online mirror of Romania's IOI 2017 Selection Contests. The first contest already took place on Saturday.

The second round will take place tomorrow, Monday, 08/May/2015 06:30:00 (UTC). The round will be rated for all users. You will have to solve 3 problems in 5 hours. The statements will be available in English and Romanian.

The third round will take place on Wednesday. As for the first round, we'll host the online mirror on Friday. Rounds 4, 5 and 6 will take place in a few weeks.

Contest format:

• You will have to solve 3 tasks in 5 hours.
• There will be full feedback throughout the entire contest.
• The tasks will have partial scoring. The maximum score for each problem will be 100 points.
• There will be no tie breaker, so two users having the same total score at the end of the contest will share the same place in the standings.

If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #27 will take place on Wednesday, 03/May/2017 15:00 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 7 tasks of varying difficulty that need to be solved in 2 hours.

One of the problems is going to be interactive. You can read more about interactive problems here.

Contest format:

• You will have to solve 7 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Later Edit:

Congratulations to the winners:

1. LHiC
2. dreamoon_love_AA
3. Um_nik
4. atatomir
5. mmaxio

Also, the editorial has been published. Hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #26 will take place on Tuesday, April/25/2017 15:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

• 1 random prize for the top 20%
• 1 random prize for the next 30%
• 1 random prize for the bottom 50%

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Later Edit:

Congratulations to the winners:

1. Irineu
2. Sisu
3. mnaeraxr
4. Twoflower
5. Slamur

Also the Div. 1 winners:

1. Deemo
2. Bedge
3. kmjp
4. satyaki3794
5. IMAN_GH

And the 3 lucky prize winners:

1. Sisu
2. FelixMP
3. elistark

Also, the editorial has been published. Hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #25 will take place on Tuesday, April/18/2017 15:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

• 1 random prize for the top 20%
• 1 random prize for the next 30%
• 1 random prize for the bottom 50%

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Later Edit:

Congratulations to the winners:

1. jonathanirvings
2. Pepe.Chess
3. platypus179
4. ha1vanka
5. AlexFetisov

Also the Div. 1 winners:

1. Deemo
2. atatomir
3. sugim48
4. lucyanna2018
5. maximumSHOT

And the 3 lucky prize winners:

1. RazvanD
2. tudor4
3. anik_JU

Also, the editorial has been published. Hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #24 will take place on Tuesday, 11/Apr/2017 15:00 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 7 tasks of varying difficulty that need to be solved in 2 hours.

We are honoured to have Arterm as problem setter.

Contest format:

• You will have to solve 7 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Later Edit:

Congratulations to the winners:

1. Lewin
2. rajat1603
3. Reyna
4. black_horse2014
5. uwi

Also, the editorial has been published. Hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #23 will take place on Tuesday, April/04/2017 15:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

• 1 random prize for the top 20%
• 1 random prize for the next 30%
• 1 random prize for the bottom 50%

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Later Edit:

Congratulations to the winners:

1. scanhex
2. VladGavrila
3. bogdan10bos
4. RomeoFantastik
5. mariand

Also the Div. 1 winners:

1. kmjp
2. lucyanna2018
3. visanr
4. HellKitsune
5. Andrei1998

And the 3 lucky prize winners:

1. rapel
2. GreenGrape
3. rubick

Also, the editorial has been published. Hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #22 will take place on Monday, March/27/2017 14:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

• 1 random prize for the top 20%
• 1 random prize for the next 30%
• 1 random prize for the bottom 50%

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Don't forget to like us on Facebook, VK and follow us on Twitter.

We recently open-sourced a large part of our front-end code, and wrote a blog post about it.

It also talks about the path from competitive programming to working on real-world software development, and how me hope it becomes a road more traveled.

Out of curiosity, what are you guys thoughts about moving from competitive programming to the software industry, or spending time at both?

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #21 will take place on Sunday, 19/Mar/2017 15:00 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 7 tasks of varying difficulty that need to be solved in 2 hours.

We are honoured to have desert97 as problem setter.

More contests, never miss them again

The platform has reached a certain level of maturity that allows us to organise more contests from now on. We have created an event on Facebook. You only need to join once, and you will be notified every time we host a new round.

Contest format:

• You will have to solve 7 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Edit

Due to some unexpected events, we had to move the start of the contest one hour later.

Later edit

Congratulations to the winners:

1. I_love_Tanya_Romanova
2. izban
3. LHiC
4. lucyanna2018
5. W4yneb0t

Also, the editorial has been published. We hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #20 will take place on Tuesday, March/07/2017 16:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Platform redesign

We have given the site an entire new look. The new navigation sidebar can be found by clicking in the upper left corner of the page, while the global chat and latest forum posts are easily accessible from the upper right corner. We also changed the front page and the blog. We hope you're going to like the new look.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #19 will take place on Friday, February/24/2017 16:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #18 will take place on Sunday, 12/Feb/2017 18:30 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 8 tasks of varied difficulty that need to be solved in 2 hours and 30 minutes.

We are honoured to have desert97 as problem setter.

Contest format:

• You will have to solve 8 tasks in 2 hours and 30 minutes.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

EDIT:

Congratulations to the winners:

1. Um_nik
2. andrew.volchek
3. Reyna
4. IvL
5. LHiC

We hope you enjoyed the contest!

Hello, Codeforces!

We are happy to announce that we're going to start a new series of contests at csacademy.com. If you are planning to interview for a software engineering position, the interview contests are a great place to hone your skills. We also think they are going to be challenging for regular algorithms enthusiasts.

Interview Contest #1 will take place on Saturday, January/28/2017 16:00 (UTC). If you want to take part in this round you need to register before the contest begins. You will have to solve 8 tasks of varied difficulty in 2 hours. The contest will also feature an interactive problem.

Contest format:

• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #17 will take place on Thursday, January/26/2017 16:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1600. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello Codeforces!

It's been a while since our last blog post. We've been working hard on several features that we are happy to share with you.

Gmail spam

First of all, we suspect some of our users using gmail didn't get our last emails, as they were considered spam. If you wish to further receive emails from us please check your spam folder and move the emails to inbox.

Enforced templates

All the interview problems, except for those that were used in CSA rounds, now support enforced templates in C++, Java, Python and Javascript. Basically, the template takes care of reading the input, calling the function you need to implement and printing the result. You can concentrate on solving the problem, not having to worry about all the messy details.

Interviews

This new section allows you to take an interview on demand. You can choose the difficulty and duration. The tasks are selected from those you didn't solve yet in the interview archive. You can access the interview section here.

Hourly contests

Every half-hour, a contest starts on CS Academy: every full hour highlights an algorithms-style contest and every hour-and-a-half an interview-style contest. This feature was introduced to reach a a few different points:

• give users an incentive to stay on the website for a longer period of time
• bring old but great problems back into attention
• add a bit of competitiveness outside our regular rounds
• most of all, make the problem-solving experience a bit more fun

The problems are chosen from the archives, in a way that tries to ensure none of the participants had previously solved them.

Rating changes

As some of you noticed, we had a bug in the rating algorithm. We fixed it and recalculated all the ratings. We decided to change the cutoffs for red at 1700 and for yellow at 1600.

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #16 will take place on Sunday, 11/Dec/2016 12:00 (UTC). If you want to take part in this round you need to register before the contest begins.

This contest will be a Div1 + Div2, with 7 tasks of varied difficulty that need to be solved in 2 hours. ALL 7 problems will be interactive. Check out our blog post for more details about interactive problems.

Many thanks to Yury_Bandarchuk for translating the problem statements in Russian.

Contest format:

• You will have to solve 7 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Platform changes since Round #15

• Added interactive problems
• Added analysis section for contests

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello Codeforces!

During the past few weeks we've been working on modifying the jailer system to support interactive problems. You can read more about them in this blog post.

Right now we have 3 basic problems in the archive, but we are concerned the system might still have some bugs. So we'd like to ask for your help. We are particularly interested in:

• Wrong solutions that get an OK verdict
• Correct solutions that get a WA verdict (or TLE, MLE, RE).

We'd like to go through these checks as fast as possible, because we have a surprise prepared for the next contest.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #15 will take place on Wednesday, 30/Nov/2016 16:00 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 7 tasks of varied difficulty that need to be solved in 2 hours and 30 minutes.

We are honoured to have josdas and bluemmb as problem setters.

Also many thanks to Yury_Bandarchuk for translating the problem statements in Russian.

Contest format:

• You will have to solve 7 tasks in 2 hours and 30 minutes.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Platform changes since Round #14

New forum

In the right side of the navbar, next to the blog section, you can find a link to our forum:

... and it looks like this:

The forum is build as a single page app, so you don't need to refresh the page to see new changes (votes and new posts update in real time).

Geometry tool

You can find it in the Apps section, below the Graph Editor:

More languages added

During the contest we don't guarantee the time limits will be calibrated for languages other than C++ and Java.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #14 will take place on Monday, November/14/2016 17:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1550. Unrated users will also be affected. High rated coders can participate unofficially.

Many thanks to Yury_Bandarchuk for translating the tasks in Russian.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Platform changes since Round #13:

• Navbar redesign
• Contest scoreboard filter added

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

EDIT:

Congratulations to the winners:

1. dragoon
2. NikaraBika
3. hey_boris
4. the_art_of_war
5. fanache99

And also to the Div. 1 winners:

1. vintage_Vlad_Makeev
2. atatomir
3. Deemo
4. Doge
5. dreamoon_love_AA

We hope you enjoyed the contest!

EDIT2: Check out our new forum.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #13 will take place on Thursday, 27/Oct/2016 16:00 (UTC). If you want to take part in this round you need to register before the contest begins. Just like the previous rounds, this will be a Div1 + Div2, with 7 tasks of varied difficulty that need to be solved in 2 hours and 30 minutes. We are honoured to have josdas, I_Love_Tina and atatomir as problem setters.

We'd also like to thank Yury_Bandarchuk for translating the statements in Russian.

This round is going to have some money prizes, as follows:

• First place: 125$
• Second place: 100$
• Third place: 75$
• Fourth and fifth place: 50$
• After the contest ends we may decide to award one or more special prizes on subjective basis.

Contest format:

• You will have to solve 7 tasks in 2 hours and 30 minutes.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Round #11 winners

As we announced before Round #11, we were supposed to award two more special prizes. Again, we decided to choose the winners randomly, using the same algorithm as in the previous rounds. So the winners of the two special prizes, each worth 50$, are Ra16bit and ajinkya1p3. The two will be contacted soon via email.

Platform changes since Round #12

New archive design

As you can see above, we've made some pretty drastic changes to the way our archive looks.

Tags and difficulty

We've also added tags and difficulty to all the existing problems. The tags are of two types: first level tags act like categories and they can nest second level tags. Clicking on a tag displays only problems having that tag OR, in the case of categories, at least one of its nested second level tags.

The difficulty of the problems falls in four categories: easy, medium, hard and hardest.

Multiple workspaces

You can now have up to 10 different workspaces. Each of them is a collection of files, one for each supported language.

Code sharing — now easier than ever

Whenever you compile/run a source, a "Share" button appears to the left of the "Compile" one. You can copy the url and then paste it wherever you want. Accessing the link opens a page like this (notice the "Fork" button):

Forking a source creates a new workspace and initialises it with the shared code.

New interview archive

Although not fully public yet, we'd like to share with the Codeforces community our new interview archive. It currently has 24 problems, some of them from previous CSA rounds, others are brand new. The idea behind this new project is to become a useful tool for everyone who is preparing for interviews with some of the top IT companies in the world. The purpose of these problems in not to AC them, but to help you learn how to explain your solution. Check out the editorials for an example.

We tried to provide you with a unique experience, many tasks supporting interactive widgets as you can see below:

^ Task Min Max Subarray

^ Task Justify Formatting

Task workspace split view

And the final platform change, we modified the task workspace such that split view works not only with the problem statement, but with all the other tabs too (editorial, submissions, etc).

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #12 will take place on Thursday, September/15/2016 16:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1550. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. Unlike the previous rounds, this will be Div. 2. It will consist of 5 tasks of more accessible difficulty.

Many thanks to Yury_Bandarchuk for translating the statements in Russian!

Platform changes since Beta Round #11:

• Worked on improving the platform stability.
• The workspace now works even if you are not logged in.

Contest format:

• You will have to solve 5 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #11 will take place today, Monday, 22/Aug/2016 16:30 (UTC). If you want to take part in this round you need to register before the contest begins. Just like the previous rounds, this will be a Div1 + Div2, with 7 tasks of varied difficulty. We are honoured to have Alex7 as a problem setter.

This round is going to have some money prizes, as follows:

• First place: 125$
• Second place: 100$
• Third place: 75$
• Fourth and fifth place: 50$
• Two more special prizes, each consisting of 50$. The criteria for the special prizes is not chosen yet, but we will make it public after the contest.

Contest format:

• You will have to solve 7 tasks in 2 hours.
• There will be full feedback throughout the entire contest.
• Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
• Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
• Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

• Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
• Solutions that don't compile or don't pass the example test cases are ignored.
• Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.

Hello, Codeforces!

The series of contests dedicated to IOI 2016 will come to an end tomorrow with IOI 2016 Training Round #5. We will again use problems from past Romanian competitions. For this reason, the round will be unrated.

The contest will take place on Sunday, Aug/07/2016 08:00 (UTC). This round will be more difficult than the previous ones. Don't forget to register in order to participate.

Contest format:

• You will have to solve 4 tasks in 4 hours.
• There will be full feedback throughout the entire contest.
• The tasks will have partial scoring. The maximum score for each problem will be 100 points.
• There will be no tie breaker, so two users having the same total score at the end of the contest will share the same place in the standings.

The problem authors for this round are Cosmin Negrușeri, mugurelionut and Mihai Pătrașcu.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at contact@csacademy.com

Don't forget to like us on Facebook, VK and follow us on Twitter.