Hello, friends!

Yes, this post is for friends of Codeforces. Recently Codeforces had 5 years birthday. And on this occasion we opened a campaign to raise funds for the operation and development of Codeforces.

We are eager to develop and move forward and look forward to your participation in the campaign.

We invite you to consider the possibility to support Codeforces. Details of the campaign can be found at its direct link.

Mike Mirzayanov

UPD: We have great news!

Hello, Codeforces!

I'd like to invite you to Codeforces Round #293 (Div. 2). It will be held on Tuesday, February 24 at 19:30 MSK and as usual Div. 1 participants are invited to join out of competition.

Great thanks to Maxim Akhmedov (Zlobober) for helping me preparing the contest, to Maria Belova (Delinur) for translating the statements into English, to Mike Mirzayanov (MikeMirzayanov) for the great Polygon platform and ideas of some problems and to my dear friends Pavel Kholkin (HolkinPV), Arthur Svechnikov (ikar) and Vitaliy Kudasov (kuviman) for writing solutions.

It will be a little unusual round — you will be given six problems and two and half hours to solve them.

UPD Score distribution will be 500-1000-1500-2000-2500-2500. Good luck everyone!

UPD2 Competition completed! Thank you all!

UPD3 You can find editorial here.

UPD4 Congratulations to the winners!

1. urkkvr145
2. 0o00oo0o000oo00o
3. sorry_t0nyukuk
4. NgocHai
5. GintokiSakata

Hello, everyone! Codeforces Round #292 will be held at Feb/17/2015 19:30 MSK. We're looking forward to your participation!

The problems are from dreamoon_love_AA, and thanks Shik for some discussion. Also we want to thank Zlobober for helping me prepare the round, AlexFetisov and winger for testing this round , Delinur for translating the statement into Russian, and MikeMirzayanov for Codeforces and Polygon.

This is first time I provide all problems for a Codeforces round. I hope you'll find it interesting! Please read all problem statements and discover what the main character drazil do in those problems for he's really cute =)

Finally, I would like to ask sorry_dreamoon to participate this round. I believe everyone have the same curiosity as me about your behavior in Dreamoon's round =) May I have the honor of inviting you?

Update1 : Because problems of this round are hard to determine their difficulty, We will use Dynamic score for this round. Then the order of problems is from easy to hard by sense of me and testers.

Update2 : Due to technical reasons we have to move round on five minutes.

Update3 : Congratulation to our winners:

Div 1:

1. Haghani

2. sorry_dreamoon

3. Endagorion

4. jcvb

5. xyz111

Also, special congrats on rng_58, who solved problem E in Div.1, which anyone else could not solve.

Div 2:

1. EarthQuito

2. I.Smirn0ff

3. zclimber

4. Chipe1

5. tylerbrazill

Between them, EarthQuito is the only person who solve all problems!

Update4 : link to editorial

Hello, Codeforces!

I'd like to invite you to Codeforces Round #291 (Div. 2). It'll be held on Saturday, February 14 at 19:30 MSK.

Great thanks Maxim Akhmedov (Zlobober), Vasya Antoniuk (Antoniuk) for helping me preparing the contest, to Maria Belova (Delinur) for translating the statements into English, to Mike Mirzayanov (MikeMirzayanov) for the great Polygon platform.

Good luck everyone!

UPD: Score distribution will be the next — 500-1000-2000-2000-2500.

UPD: Editorial. Sorry for the delay)

Are you in love with algorithms? If you are don't miss this round and be algorithm's valentine ;)

On the night before valentine's day (exact time), Valentine Algorithm cUp 2015 is going to take place.

There will be 6 problems and 3 hours to solve them. All of them are written by me(PrinceOfPersia).

This competition is like surprise languages but too different. 3 days before the contest, I will publish tutorial of 5 new algorithm languages(not programming languages) with their compiler codes. Each language is going to be really simple to learn and have at most 6 or 7 commands (they're not like programming languages).

Your program should print the code written in the language the problem says and checker will run it (pay attention that inputs are encoded, don't try to read form input, just print the code). Don't use unnecessary wjitespaces.

Each command of a language, will have a number, shown by w(x) called order. There will be a counter cnt = 0 (initially), every time your code calls this command, cnt increases by x. The order of your code equals the final value of cnt.

Each problem has a limit for your code's order.

If your code gets CE or OLE (order limited exceeded) or WA, you will receive Wrong answer.

Example :

Language (named EXM) : This language is built to process on an integer. There are two valid commands :

1. M x : multiply the number by x. (Order : w(x) ).
2. I x : increase the number by x. (Order : w(1) ).

Your program returns the final value of that number.

Your task is given number n, the return value of your code must be number 2n + 1 .

Code in EXM:

M 2
I 1

C++ code (the code you will submit in submit page):

printf("M 2\nI 1\n");

Your code's order will be 2 + 1 = 3 .

UPD: You can download languages tutorial and their compilers here.

Attention: Compile the code for each language, in Windows : g++ -o lang lang.cpp -O2 -std=c++0x and in Mac and Linux g++ -o lang.out lang.cpp -O2 -std=c++0x.

Using in Windows:

For running your code that is saved in a file like x.txt, use exactly lang x.txt in cmd and if you want debug mode enabled, use lang x.txt -d (not lang -d x.txt).

Using in Mac OS X or Linux:

For running your code that is saved in a file like x.txt, use exactly ./lang.out x.txt in terminal and if you want debug mode enabled, use ./lang.out x.txt -d (not ./lang.out -d x.txt).

Sample problem:

Write a program in Prolan that given a string s containing only a and b deletes all bs and converts all as to d. Order shouldn't exceed 10⁶ (1 ≤ |s| ≤ 100).

My code:

(b,)
(a,d)

If you have any question, feel free to ask.

UPD2: Scoring will be 500-1000-1500-2000-2500-3000.

By the way, the main characters of each problem is different from other problems. Actually, for each problem the main characters are an imaginary(or not!) couple :)

UPD3: IDXT's compiler had some bug, you can download the correct source here.

UPD4: For people who want to practice, the new archive(including languages tutorials and bugless compilers) can be found here.

Hello Codeforces community,

I am happy to announce that Rocket Fuel Inc. will be hosting a Rockethon competition again! The contest is prepared by Rocket Fuel employees Eldar Bogdanov, Anton Lomonos, Lasha Lakirbaia, Alexander Ruff, Nikhil Goyal and me, Ievgen Soboliev. We hope everyone will find some interesting problems in the contest and everyone will have as much fun solving these problems as we had preparing them. Just like last year, the best participants will receive valuable prizes and top performers will get Rockethon 2015 T-shirts! Also, Rocket Fuel is interested in hiring people after this event, so please fill out the simple form during registration.

About Rocket Fuel

Rocket Fuel is building technology platform to do automatic targeting and optimization of ads across all channels — display, video, mobile and social. Our pitch to advertisers is very simple "If you can measure metrics of success of your campaign, we can optimize". We run campaigns for many large advertisers and our clients include many top companies within the following industries: autos, airlines, commercial banks, telecom, food services, insurance, etc. Examples include BMW, Pizza Hut, Brooks Running Shoes and many more!

We buy all our inventory through real time bidding on ad exchanges like Google and Yahoo. Ad exchanges are similar to stock exchanges except the commodity being traded is ad slots on web pages. Our serving systems currently process over 60B bid requests/ day with a response time requirement of 100ms. Our data platform has 64 PBs data that is used for analytics as well as modeling.

Our engineering team is still small (~150) enough for any one person like yourself to make a huge impact. The team represents many top schools in US and outside — Stanford, Carnegie Mellon, MIT, Wisconsin-Madison, IIT (India), Tsinghua (China).

Rocket Fuel has been named #4 on Forbes Most Promising Companies in America List in 2013 and #1 Fastest Growing Company in North America on Deloitte’s 2013 Tech Fast 500 and our CEO George John was recently named “Most Admired CEO” by the SF Business Times in 2014.

My Personal Story

About one year ago I visited CodeForces and saw an announcement of Rockethon 2014. My first thought was "Another competition from a big company, that's nice!". I took part in this contest, performed quite well and recruiters from Rocket Fuel have contacted me and scheduled some interviews. I passed the interviews and now I'm here, in Rocket Fuel.

It has been a nice opportunity to learn advanced concepts of software engineering from a huge amount of smart people working with you. Also, our activities here are not limited only to writing code — we do fun things here like playing basketball, soccer, table tennis. I invite everybody to take a part in the competition and would be glad to hear if any of you thinking about joining Rocket Fuel.

Contest Overview

The contest will begin on February 7, 9AM PST.

The contest length is 3 hours.

The testing of each submission will be performed as soon as the submission is received and the verdict will be delivered to the submission author right away.

The problemset will consist of 7 problems. Each problem can contain from one to three subproblems. Each subproblem will be worth a fixed amount of points. The ties between contestants with the same score will be broken by penalty time which is computed similar to ACM scoring system.

Prizes

The top three contestants will receive the following prizes:

1) IPhone 6 (16 Gb)

2) Participant can choose Apple Watch or Samsung Gear S

3) Participant can choose Apple Watch or Samsung Gear S

The top 150 performers will receive a Rockethon T-shirt designed specially for this contest.

If you are unable to take part in the competition but are interested in joining Rocket Fuel, we will be screening resumes submitted through the special form.

Fox Ciel is back!

I invite you to participate in Codeforces Round #290, which will start at the standard time on next Monday:

This is my 4th round on Codeforces, my previous rounds: #190, #228, #270.

Last Div1 Round (#286) is so hard, so after notice that, we decide to reduce the difficulty of this round. (For example, current Div1-E was used as Div1-D) I hope more people can enjoy all tasks in this round: this time no task requires advanced knowledge like linear space or Fourier Transform.

The background story will be Fox Ciel's life: learning programming, play games, traveling, have dinner and so on.

Like Round #228, top-20 contestants that are currently at Petrozavodsk training camp will be rewarded with nice Codefores T-Shirts. Contestant may be a team member, jury, coach, organizer, or whoever else involved in camp, no matter of status.

As usual, thanks to Zlobober for giving great suggestions and test my round, and MikeMirzayanov for the platform (Codeforces and Polygon).

Good luck and have fun!

Update1: Score Distribution is ... Div2: Standard (500 — 1000 — 1500 — 2000 — 2500), Div1: a bit unusual ... (500 — 1000 — 1500 — 2250 — 2250)

Update2: Editorial: http://codeforces.net/blog/entry/16173

Update3: Congratulation to our winners:

Div1:

1. Petr

2. Endagorion

3. mmaxio

4. jqdai0815

5. tourist

They are all people who solved 5 tasks!

Div2:

1. SkullSkin

2. joshkirstein

3. gabrielinelus

4. UnknownNooby

5. Andrey_WK

The third round of Facebook Hacker Cup 2015 will take place exactly one week after round 2: on January 31st at 9:00 PM UTC. The round will last 3 hours. Top 25 participants will win a trip to Menlo Park to participate in the final round, which will take place at Facebook office on March 6th.

Participants will be able to enter the contest using this link, and the scoreboard will be available to everyone here.