By MikeMirzayanov, 9 years ago, translation, In English

Hello, Codeforces!

As you know the Linux package managers make life easier for users and administrators. In the Windows world, this is much worse, although there are some tools (in Windows 10 it will be much better): nuget, chocolatey, wpkg and others.

Maintaining Codeforces testing servers, computers of Programming Competitions Training Center of Saratov SU, installing workstations for different olympiads I finally got tired to write a variety of bat-files and decided to regularize the process.

Chocolatey makes good help, but in the details it turned out that it can't used in some cases: you can not specify the installation directory, there is no support for private repositories, lack of some packages, Chocolatey packages do not contain installers but only links for them (if package's official is down, one can't install the package).

That's why, in December 2014, I spent out several evenings to work on a package manager most convenient for our purposes (called PBOX, reads like a pi-box). I'm considering using PBOX to install specific software for Codeforces (concrete compilers and tools), but for programs of general purpose it is good idea to use Chocolatey.

In the coming months all the Codeforces testing servers (and many other computers of the CS department of Saratov State University), I plan to reinstall, and use in particular PBOX.

I have little use it for personal purposes, it seems to me, PBOX may be useful to someone from Codeforces users. The site http://pbox.me has usage examples. Below are a few explanations.

Installation

Visit http://pbox.me and in the administrative Windows console (search for cmd.exe, get the context menu by right mouse button, select Run as administrator) run the code from the website home page. PBOX written in Java, if you're not have it, then it will download JRE automatically. By the way, every time you start PBOX, it will try to self-update, so forget about updating it manually.

I usually turn off UAC, if you do not want you will always need to use administrative console. You can disable UAC by typing pbox -uac.

Usage

Do you want to install exactly the same g++ as Codeforces has? Just run pbox install mingw-tdm-gcc. It will install it to %HOMEDRIVE%\Programs\mingw-tdm-gcc (by default), add to PATH some directories (including MSYS), add environment variable MINGW_HOME.

Generally, to see exactly what will happen on installation simply visit the site to find the package and click Show pbox.xml.

For now PBOX has only 73 packages. Visit http://pbox.me/packages to explore them.

I like the collection of useful utilities called tools, so just run pbox install tools to install sysinternals tools, windows resource kit, support tools, and others like curl, wget, imdisk (add all of them to PATH). BTW, useful utility runexe.exe will also be installed: it is good to run processes and see time/memory usage.

Most compilers and tools will be installed to C:\Programs (actually to %HOMEDRIVE%\Programs). Quite convenient to have a path to them short and with no spaces unlike "Program Files".

You can use additional options like pbox install far --homedir=C:\Far --arch=32 --version=3.0.4040. To uninstall a package you can run: pbox uninstall far. Here are more examples of usage:

Description Command line
Ask PBOX to forget that it installed a package (but do not uninstall it) pbox forget <package>
Print package information (you can specify the version) pbox info <package> или pbox info <package> --version=version
Find package by title/description/tag pbox find <query> or pbox search <query>
Find package (find in all versions, not the latest only) pbox find <query> --all или pbox search <query> --all
Print all the packages in repository (latest versions or all) pbox list или pbox list --all
Print the list of all the installed packages pbox list-installed

Download a package and explore it

It is really easy. Just try: http://repo.pbox.me/1.0/jdk8/1.8.0_45/jdk8$1.8.0_45.pbox.7z

Source code

Visit: https://github.com/MikeMirzayanov/pbox

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By PrinceOfPersia, 9 years ago, In English

Codeforces round #305 is gonna take place soon and I'm the writer.

After my previous contest that many people think it was a hard contest, I prepared an easy contest to cheer you up!

I want to thank Haghani for testing this round, Zlobober for help me prepare this round and his great advises, Delinur for translating problem statements into Russian, mruxim and Yasser Ahmadi Phoulady (Rasta) for their advises and ideas, HosseinYousefi for helping me choose legends and graphics and MikeMirzayanov for great Codeforces and Polygon platform and guys from Physics Olympiad that kept disturbing me while preparing this round.

This is my second official round and I hope you enjoy it.

The main character of this round is gonna be Mike (I didn't say MikeMirzayanov :D).

Also you'll meet Xaniar and Abol.

I wish you all Successful hacks and Accepted solutions and high ratings.

Scoring will be posted soon.

GL & HF!

UPD: Scoring is:

  • Div.2: 500-1000-1750-2000-2750
  • Div.1: 750-1000-1750-1750-2500

UPD2: Due to technical reasons we moved the round by 5 minutes.

UPD3: Contest has just ended. You can find the editorial here.

UPD4: System testing is done.

Congratulations to the winners, specially dreamoon_love_AA that got to his goal !

Div.1 winners:

  1. dreamoon_love_AA
  2. HYPERHYPERHYPERCUBELOVER
  3. jqdai0815
  4. YuukaKazami
  5. subscriber

Div.2 winners:

  1. fromWork
  2. IloveGoodness
  3. norge
  4. rumman_sust
  5. williamzpf

See you in the next rounds.

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By Al.Cash, 9 years ago, In English

This is my first attempt at writing something useful, so your suggestions are welcome.

Most participants of programming contests are familiar with segment trees to some degree, especially having read this articles http://codeforces.com/blog/entry/15890, http://e-maxx.ru/algo/segment_tree (Russian only). If you're not — don't go there yet. I advise to read them after this article for the sake of examples, and to compare implementations and choose the one you like more (will be kinda obvious).

Segment tree with single element modifications

Let's start with a brief explanation of segment trees. They are used when we have an array, perform some changes and queries on continuous segments. In the first example we'll consider 2 operations:

  1. modify one element in the array;
  2. find the sum of elements on some segment.

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By yeputons, 9 years ago, In English

I've just discovered this question on Quora: What is the story behind your username at CodeForces?. I guess it'd be pretty interesting to hear stories from top participants. For instance, my handle's history is already described there.

This blog is dedicated to everyone who don't have Quora account, so you can share your histories and comments here.

I personally would love to hear stories from tourist, rng_58 and YuukaKazami from current top-10.

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By Radewoosh, 9 years ago, In English

Hi everyone!

I am pleased to announce that Codeforces Round #304 (Div.2), of which I am the author, will take place today. This will be my first round, so I hope that it will be cool and interesting. Traditionally Div.1 participants can take part out of the competition.

I want to thank znirzej, Dakurels and Zlobober for help with preparing the problems, thank Delinur for translating the problems, and thank to MikeMirzayanov and all who created polygon for this great system.

I wish you all good luck!

UPD Scoring will be 500-1000-1250-1500-2250.

UPD editorial

UPD Congratulations for winners in div.2:

  1. phoenix__jpn
  2. Hujishiro_otone
  3. lzw4896s
  4. jinzhao
  5. jabbawookiees

And in div.1:

  1. ngfam_kongu
  2. uwi
  3. anta
  4. W4yneb0t

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By MikeMirzayanov, 9 years ago, translation, In English

Hello!

Only a few hours before the start of ACM-ICPC World Finals 2015!

The ACM ICPC is considered as the "Olympics of Programming Competitions". It is quite simply, the oldest, largest, and most prestigious programming contest in the world.

The ACM-ICPC (Association for Computing Machinery — International Collegiate Programming Contest) is a multi-tier, team-based, programming competition. Headquartered at Baylor University, Texas, it operates according to the rules and regulations formulated by the ACM. The contest participants come from over 2,500 universities that are spread across 100+ countries and six continents.

This year the best 128 teams in the world will meet face to face in Marrakech on World Finals. Video coverage will start on 09:00 (UTC), and the contest will start on 10:00 (UTC).

Good luck to all the teams!

UPD Added link to the text coverage on tumblr.

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By seland, 9 years ago, translation, In English

Hello everyone!

I am glad to announce that soon will Codeforces Round #303 for Div.2 paricipants, the author of which I am. Traditionally Div.1 participants can take part out of the competition.

This is my first round, and I hope that it will be interesting.

Round wouldn't take place without the help of the Codeforces team! Great thanks to Zlobober for helping me preparing the round and Delinur for translation. Special thanks to everyone who puts his effort into the creation and maintenance of Codeforces and Polygon systems.

Score distribution will be announce later.

Good luck and inspiration!

UPD Score distribution will be — 500-1000-1750-1750-2500.

UPD Congratulations for winners in Div.2:

  1. Bell-sama
  2. anko
  3. BobDylan
  4. Gusheng
  5. Diguised
  6. imyyimdog

And in Div.1:

  1. ngfam_kongu
  2. Laakeri
  3. Um_nik
  4. KrK

UPD Link for editorial.

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By Aksenov239, 9 years ago, translation, In English

Hi everybody from the ICPC Live team (elizarov, pashka, niyaznigmatul, Egor, lperovskaya and me).

We want to inform you, that broadcast of the World Finals will take place on Wednesday, 20th of May.

The broadcast will be on the two websites (youtube and twitch). The links will be posted tomorrow, but you could subscribe to our channel.

We will have the following schedule:

Don't forget to subscribe on our channels on youtube and on twitch: icpclive1 and icpclive2.

While you wait, on Tuesday, May 19 Dress rehearsal will take place. The broadcast will be available on the youtube channel ICPC Live and on the twitch channel ICPC Live. The idea of this broadcast is to check, if everything is fine, so, please, be nice and report availability or performance issues. We can't guarantee the good broadcast.

Regards, Team ICPC Live

UPD: Read live ICPC Finals text broadcast. http://icpcnews.tumblr.com/post/119424970944/world-finals-live

UPD2: youtube

UPD3: twitch, main screen, twitch, split screen

UPD4: Thanks to alexyz for the link: multitwitch

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