vepifanov's blog

By vepifanov, 7 months ago, translation, In English,

ACM ICPC World Finals 2016. Phuket, Thailand.

Harvard University team: Johnny Ho (random.johnnyh), Scott Wu (scott_wu), Calvin Deng (dnkywin), Jelani Nelson (coach) (Robert L. Walton, Coach). Team got 3rd place (gold medal) and became North America region Champions.

Main contest.

What is it? Scott Wu communicates with an outside adviser? Team has more than three participants?

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By vepifanov, 12 months ago, translation, In English,
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By vepifanov, 12 months ago, translation, In English,

Intel Code Challenge Final Round will take place on Saturday, 8 October 15:05 MSK.

All users of the Codeforces can participate in it as in an usual round. The round will be rated and both divisions can participate. Pay attention to the time of the beginning of the round.

There will be 7 problems with statements in english and russian languages and 3 hours to solve them. Scoring distribution will be announced closer to the start of the round.

The problems were prepared by me — Vladislav Epifanov (vepifanov). I want to say thanks to Alexey Shmelev (ashmelev), Alexander Fetisov (alexfetisov) and Vladislav Isenbaev (winger) for testing the problems, coordinator of the Codeforces Gleb Evstropov (GlebsHP) for his help with the contest preparation, and Mike Mirzayanov (MikeMirzayanov) for the Codeforces and Polygon systems.

UPD. Scoring distribution: 500-1000-1500-1500-2500-2500-2500. Since the round will be 3 hours long, the number of points for each task will decrease slower than in usual round.

UPD. 2 Due to some issues on one of sites for official participation in Intel Code Challenge we shifted the beginning of the round for 10 minutes. Sorry for the inconvenience.

UPD. 3

Final rating changes will be available after removing unfair participants.

Editorial will be published on Sunday, 9 October.

Editorial

UPD. 6

Photos from the onsite event.

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By vepifanov, 13 months ago, In Russian,
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Tutorial is loading...
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By vepifanov, 13 months ago, translation, In English,

Intel Code Challenge Elimination Round will take place on Saturday, 1 October 17:05 MSK. Only russian citizens from 18 to 27 years old can officially participate in this competition.

However, for all other users of the Codeforces it will be an usual round. The round will be rated and both divisions can participate.

There will be 6 problems and 2 hours to solve them. Scoring distribution will be announced closer to the start of the round.

The problems were prepared by me — Vladislav Epifanov (vepifanov). I want to say thanks to Alexey Shmelev (ashmelev), Alexander Fetisov (alexfetisov) and Vladislav Isenbaev (winger) for testing the problems, coordinator of the Codeforces Gleb Evstropov (GlebsHP) for his help with the contest preparation, and Mike Mirzayanov (MikeMirzayanov) for the Codeforces and Polygon systems.

UPD. Scoring: 500-500-1000-1500-2000-2500.

UPD 2.

I must apologies for the problem C. We decided to simplify it in the last moment, and it turned out, that the simplified version of it already appeared on another online judge.

Anyway, I hope that the second round will be better than the first one.

Editorial for this round will be published on Sunday, 2 October.

UPD 3. Editorial

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By vepifanov, 13 months ago, In Russian,

Независимо от того, официально вы будете участвовать в Intel Code Challenge или нет, участие в раундах на Codeforces будет открыто для всех. У всех участников будет пересчитан рейтинг.

Корпорация Intel проводит соревнование по программированию Intel Code Challenge (http://codechallenge.ipdnn.com/), приуроченное к крупной технологической партнерской конференции Intel Partners Day.

Победители соревнования будут награждены ценными призами, а также поездкой на технологическую конференцию, которая пройдёт в г. Нижний Новгород. Главный победитель, набравший по итогам соревнования наибольшее количество баллов, получит возможность посетить одно из международных научных событий.

В соревновании могут принять участие граждане РФ в возрасте от 18 до 27 лет.

Соревнование будет проводиться на Codeforces в два раунда: заочный и очный.
Для того, чтобы принять участие в Intel Code Challenge, необходимо ознакомиться с условиями проведения соревнования и зарегистрироваться по ссылке http://codechallenge.ipdnn.com/register. Город, в котором вы реально сможете принять участие во втором (очном) раунде, нужно выбрать при регистрации. Участники, зарегистрировавшиеся на Intel Code Challenge, будут разделены на группы по выбранному городу. В каждой группе 25 лучших участников первого раунда пройдут во второй этап.

Список городов, где будет проходить очный этап (тревел-грант не предусмотрен):

  • Москва
  • Санкт-Петербург
  • Нижний Новгород
  • Архангельск
  • Волгоград
  • Казань

Для участия в очном этапе конкурса необходимо будет иметь с собой ноутбук с возможностью доступа в Интернет. Длительность раундов составит 2 часа в отборочном и 3 часа в основном туре.

Раунды будут проведены по обычным правилам Codeforces.

График проведения соревнования:

  • Окончание приема заявок: 1 октября 2016 г. в 17:00 по московскому времени
  • 1-й этап (заочный) – 1 октября 2016 г.
  • 2-й этап (очный) – 8 октября 2016 г.

По итогам очного этапа соревнований в каждом из городов проведения конкурса победители получат:

  • 1 место: Микрокомпьютер Intel® Compute Stick и тревел-грант на посещение конференции «Intel Partners Day» 9-го ноября 2016 г. в Нижнем Новгороде
  • 2 место: Фитнес-браслет
  • 3 место: Внешний аккумулятор

Победитель очного этапа, набравший наибольшее количество баллов среди всех участников, получит тревел-грант на посещение одного из международных научных событий.

Оба раунда будут рейтинговыми и доступными для участия всем пользователям Codeforces.

UPD

Как указано на главной странице, заявка должна содержать следующую информацию:

  • Фамилия, Имя и Отчество заявителя
  • E-Mail
  • ВУЗ или место работы
  • Курс или должность
  • Город проживания или учебы
  • Город, в котором вы планируете проходить очный этап, если пройдете в финал
  • Логин на Codeforces

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By vepifanov, 6 years ago, In Russian,

Финал Facebook Hacker Cup 2012. В основном виды прилегающей местности.

Фото здесь.

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By vepifanov, 6 years ago, In Russian,

Финал TopCoder Open в Голливуде (Флорида, США) 25 - 29 сентября 2011 года.


Фото здесь.

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By vepifanov, 6 years ago, In Russian,

Финал Russian Code Cup в Москве 17-18 сентября 2011 года.

Фото здесь.

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By vepifanov, 6 years ago, In Russian,

Поездка сборной команды Поволжья на финал Google Code Jam 2011 в Токио.


Тексты здесь, здесь.
Фото здесь.


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By vepifanov, 7 years ago, In Russian,
 
 
 
 
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By vepifanov, 7 years ago, translation, In English,

A. Towers
The total number of towers is equal to number of different numbers in this set. To get the maximum height of the tower, it was possible to calculate for each length the number of bars with this length, and from these numbers is to choose the maximum.

B. Computer Game
Constraints in the problem allows us to solve it this way: we keep the current number of health from the boss, and current summary damage from used scrolls per second. At the next step, we choose which scrolls we can use in the current second. Of all these, we find the scroll, which causes the most damage, and apply it. If at some point we could not use any of the scrolls, and the current damage in one second does not exceed regeneration, we deduce that there are no answers. Otherwise, continue to iterate the algorithm until the number hit points will be nonnegative.

C. Old Berland Language
One of the easiest to understand solutions of this problem is as follows: sort the words in ascending order of length, while remembering their positions in the source list. We will consistently build our set, starting with the short strings: strings of length one can only be strings "0" and "1". If the number of words of length one in a set are more than two, hence there are no answers. Add the desired number of strings of length one to answer, and remove it from the current list. Then look at the string of length two: each of the remaining strings of length one can be extended in two ways (having added to each of these symbols 0 and 1). Add the desired number of strings of length two in our answer, and then increase the length of the remaining strings by one. Continue this process, until we get all words from the input set. You can see that if at some moment the number of allowable words exceeded the number of remaining, the extra words can be ignored and solution takes O (N * the maximum length of input set) time.

D. Lesson Timetable

This problem is solved by dynamic programming:

state of dynamics will be a pair of numbers - the number of current room and number of groups which have first lesson in the room with a number not exceeding the current and for which the second room is not defined yet. For each state check all possible number of groups for which the second lesson will be held in the current classroom. When you add an answer from the new state, it must be multiplied by the corresponding binomial coefficients (the number of ways to select groups which have the first lesson in next room - Xi + 1, and the number of ways to select groups which have the second lesson
in the current classroom).

 

E. Trial for Chief

First, we construct the following graph: each cell we associate a vertex of the same color as the cell itself. Between neighboring cells hold an edge of weight 0, if the cells share the same color and weight of 1, if different. Now, for each cell count the shortest distance from it to the most distant black cell (denoted by D). It is easy to see that we can construct a sequence of D + 1 repainting leads to the desired coloring:

  • The first step of color all the cells at a distance less than or equal to D in black color
  • At the second step color all the cells at a distance less than or equal to D - 1 in white
  • Etc.

Of all the cells, choose the one for which this distance is minimal, and this distance increased by one will be the answer to the problem.

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By vepifanov, 7 years ago, translation, In English,
Good evening!

Today I am the author of problems. I'm studying in Nizhny Novgorod State University (2 year, Mechanics and Mathematics). I want to thank the staff codeforces for assistance in preparing the contest, and, personally, Artem Rakhov and Maria Belova (for translations of problems into English). Also special thanks to Alexei Shmelev (NNSU) for writing alternative solutions.

P.S. Unfortunately, this round could be in error to register a team. For teams participating in this round will be counted "out of competition", ie, rating of participants does not change. If you register a team by mistake, you can unregister and register in person.

UPD: After the contest start, it will be available PDF-versions of the statements:
UPD: The contest is over, congratulate Ivan Popelyshev, who won this round. He was the only one who has successfully solved all five problems.

Link to results.


UPD: Tutorials are available.

Regards,
Vladislav Yepifanov.
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На латинице

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Announcement of Codeforces Beta Round #37
 
 
 
 
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