Conqueror's blog

By Conqueror, history, 19 hours ago, In English,

Dear CF Staff,

Can you, please, consider providing an interface to add a foreign language?

For example, I need that to do problem statements for our Regional & National Olympiads, but, at first, I could not find a way to replace default English "Input file name", "Output file name", etc. names to Kyrgyz ones, so I had to hardcode them into olymp.sty and statements.ftl.

It would be great also if one could make a several-languages statement like this

1. Page 1, Kyrgyz
2. Page 1, Russian
3. Page 2, Kyrgyz
...

or like this

1. Page 1, Kyrgyz
2. Page 2, Kyrgyz
...
N + 1. Page 1, Russian
...

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By Conqueror, history, 10 days ago, translation, In English,

Results, please?

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By Conqueror, history, 10 days ago, In English,

Hi, Chinese part of the Codeforces!

Can you, please, list the main (or the best) Chinese Online Judges and describe for what kind of problems they are known for and other interesting features of them?

Thanks, Azret

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By Conqueror, history, 10 months ago, In English,

Hello CF,

Does anybody know any contests like OpenCup competitions (Grand-Prix of *)? I feel there must at least one of such great regular online competitions with insightful problems like these.

-- Azret, IAmNomad

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By Conqueror, history, 14 months ago, translation, In English,
 
 
 
 
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By Conqueror, history, 20 months ago, translation, In English,

Hello.

I am trying to prove that sin (α - β) = sin α * cos β - cos α * sin β but getting something wrong.

OPα = (cos α, sin α)
OPβ = (cos β, sin β)
|OPα × OPβ| = |OPα| * |OPβ| * sin (γ)
|OPα| = |OPβ| = 1
γ = α - β
Hence, |OPα × OPβ| = sin (α - β)
Since, |A × B| = Ax * By - Ay * Bx
|OPα × OPβ| = cos α * sin β - sin α * cos β
Hence, sin (α - β) = cos α * sin β - sin α * cos β

But all formulas in internet say that sin (α - β) = sin α * cos β - cos α * sin β , i.e reverse of what I wrote above. Can someone find my mistake?

P.S Below is the correct proof written in white. You can find my mistake yourself first. ;)
As I understood I made mistake in computing angle. Since angles are + in counter-clockwise direction then
|OPα × OPβ| = ... * sin(360 - γ)
|OPα × OPβ| = |OPα| * |OPβ| * ( - sin (γ))
Hence, |OPα × OPβ| =  - sin (α - β)
And  - sin (α - β) = cos α * sin β - sin α * cos β
Leads to sin (α - β) = sin α * cos β - cos α * sin β

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By Conqueror, history, 21 month(s) ago, translation, In English,

Propose to all to discuss solutions here.

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By Conqueror, history, 22 months ago, translation, In English,

Hello.

Tomorrow at 23:00 UTC will be held GCJ 2016 Qualification Round.
Round will last for 27 hours. Don't forget to register!

Let's discuss problems here after the contest.

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By Conqueror, history, 22 months ago, translation, In English,

Hello.

Reading the article from e-maxx (ALERT! RUSSIAN!). A piece of code ("radix sort of equivalence classes" part):

	for (int i=0; i<n; ++i) {
		pn[i] = p[i] - (1<<h);
		if (pn[i] < 0)  pn[i] += n;
	}
	memset (cnt, 0, classes * sizeof(int));
	for (int i=0; i<n; ++i)
		++cnt[c[pn[i]]];
	for (int i=1; i<classes; ++i)
		cnt[i] += cnt[i-1];
	for (int i=n-1; i>=0; --i)
		p[--cnt[c[pn[i]]]] = pn[i];

Why p[] contains correct order of cyclic shifts of length 2k after?

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By Conqueror, history, 22 months ago, translation, In English,
 
 
 
 
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By Conqueror, history, 23 months ago, translation, In English,
 
 
 
 
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By Conqueror, history, 23 months ago, translation, In English,

Hello!

Does anybody know who will host APIO this year? Or when it will be held?

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By Conqueror, history, 23 months ago, In English,

Qualification round just ended. How to solve A, C, D?

UPD Problems — https://www.dropbox.com/s/ywyczn0m0n5q7ts/problems-e-000815.pdf?dl=0

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By Conqueror, history, 2 years ago, In Russian,
 
 
 
 
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By Conqueror, history, 2 years ago, In Russian,

Раз задачи тренировок теперь не учитываются в Положении архива, то почему бы не учесть их в отдельном Положении в тренировках?

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By Conqueror, history, 2 years ago, In English,

Hello.

Given directed unweighted graph. It consist of N ≤ 105 vertices. There is at most one edge from each vertex. You need to answer for two types of queries (Q ≤ 105):

  1. Delete an edge from vertex V. Unexisting edge won't be deleted.
  2. Find shortest path from U to V.

No ideas. How to solve it?

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By Conqueror, 2 years ago, In Russian,

Здравствуйте.

Тренировал центроидную декомпозицию на 342E — Ксюша и дерево.
Ловлю WA #12. Баг?

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By Conqueror, history, 2 years ago, In Russian,

Здравствуйте.

Сегодня прошёл Кыргызстанский Четвертьфинал ACM-ICPC 2015. Результаты доступны здесь.

Пока что архив недоступен — его закрывали на время соревнования. Скоро будет открыт. Там вы можете зарегистрироваться.

Завтра все желающие могут поучаствовать виртуально. Регистрироваться на него надо, вы будете считаться участником если сделаете >0 сабмитов.

P.S Если будете учавствовать, то рекомендуется заранее не читать задачи.

P.P.S Если не будете, то как решать A? Что-нибудь кроме венгерского алгоритма?

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By Conqueror, history, 2 years ago, translation, In English,

Hi all!

Straightly to the problem — you are given a set of N (1 < N <  = 105) distinct points with integer coordinates on coordinate plane. For each point you need to find number of closest point to it (from set, expect itself). If there are more than one output point with minimum number.  - 104 <  = xi, yi <  = 104

UPD Distance between points (x1, y1) and (x2, y2) is equal to |x1 - x2| + |y1 - y2|. :P

Input
4
0 0
1 1
1 0
0 1

Output
3 3 1 1

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By Conqueror, history, 3 years ago, translation, In English,

Hi all!

How can we add/assign arithmetic/geometric sequence in simple/persistent segment tree?

Tasks:

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By Conqueror, history, 3 years ago, translation, In English,
 
 
 
 
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By Conqueror, history, 3 years ago, In Russian,

Всем привет!

Сейчас решал задачу и тут понадобилось реализовать копирование декартова дерева, в частности у меня есть дерево T и его нужно скопировать и смержить в конец двух других деревьев. Возможно ли это сделать без обхода всего дерева?

UPD Пишу на указателях.

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By Conqueror, history, 3 years ago, In Russian,
 
 
 
 
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By Conqueror, history, 3 years ago, In English,

Hello CF!

I think many of you, in particular IOI participants, can not find a good, clear solutions of IOI problems, so I decided to create a blog where we will publish a problem then find solution for it and start to solve next problem (like on AOPS).

Let me begin — IOI 2006 B. Pyramid.

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By Conqueror, history, 3 years ago, translation, In English,
Add Participant View Participants
Name CF Handle Country Previous IOIs
Román Castellarin ponysalvaje Argentina 2013 2014
Ariel Nowik ariel.nowik Argentina No Participation
Martin Mirakyan Martin97 Armenia No Participation
Mushegh Shahinyan Mushegh Armenia 2014 S
Albert Gevorgyan albertg Armenia No Participation
Eduard Grigoryan edogrigqv2 Armenia 2010, 2011, 2013, 2014 S
Florian Leimgruber fleimgruber Austria 2014 B
Gary Ye gdisastery Austria 2013 B, 2014 B
Peter Ralbovsky peto159 Austria 2013, 2014
Simon Lehner-Dittenberger Austria No Participation
Nur Muhammad Shafiullah LamePrince Bangladesh 2012
Hasib Al Muhaimin hasib Bangladesh 2013 2014
Labib Rashid Labib666 Bangladesh 2013 2014
Imran Hasan Sherlock221b Bangladesh No Participation
Nikita Sazanovich Nik_storm_2010 Belarus No Participation
Alex Vistyazh netman Belarus 2014 S
Barbara Kuskova kuskova Belarus 2014 B
Ilya Medyanikov ferathorn Belarus No Participation
Mattéo Couplet phixyma Belgium No Participation
Damien Galant damien_g Belgium 2014
Robin Jadoul Belgium No Participation
Nico Ekkart nicoekkart Belgium No Participation
Marcelo Zeballos marcelozeballos Bolivia No Participation
Ronaldo Franco Jaldin rony Bolivia 2014
Arthur Pratti Dadalto arthurpd Brazil 2014 S
Mateus Bezrutchka m_bezrutchka Brazil 2014 S
Lucca Morais de Arruda Siaudzionis luccasiau Brazil No Participation
Murilo Corato Zanarella murilocz Brazil No Participation
Hristo Venev mustrumr Bulgaria 2012 S ,2013 G, 2014 G
Encho Mishinev Enchom Bulgaria 2013 S 2014 G
Daniel Atanasov Bulgaria No Participation
Kristian Tsaklev krisits Bulgaria No Participation
Farbod Yadegarian FarbodY Canada No Participation
Yikuan (Timothy) Li FatalEagle Canada 2014 B
Ben Zhang Kuroba Canada 2014
Jacob Jackson zxqfl Canada 2014 G
Yanyi Liu lyy China No Participation
Xiaochen Lu Ruchiose China No Participation
Yuhao Du toosimple China No Participation
Hengjie Zhang zhj China No Participation
Juan Sebastian Chaves AdamantWharf Colombia 2014
Domagoj Bradac Dbradac Croatia No Participation
Tonko Sabolcec tonkosi Croatia No Participation
Mihael Liskij Mihaell Croatia No Participation
Ivan Lazaric IvL Croatia 2013 B
Alexander Bestard Rivera bestard Cuba No Participation
Michael Gonzáles mjgonzales Dominican Republic No Participation
Manuel David Sánchez Suero tecnomaster999 Dominican Republic No Participation
Alejandra Martínez Jiménez alejandra_244 Dominican Republic No Participation
Sami Kalliomäki Scintillo Finland 2012, 2013 B, 2014 S
Tuukka Korhonen Laakeri Finland No Participation
Henrik Lievonen Hennkka Finland 2013, 2014 B
Kalle Luopajärvi zscefn Finland 2013 B, 2014 S
Alexander Tskhovrebov alexandre Georgia No Participation
Georgy Skhirtladze gskhirtladze Georgia 2014 B
Elene Machaidze emachaidze Georgia 2014 B
Giorgi Kldiashvili giorgikldiashvili Georgia No Participation
Aristofanis Rontogiannis mentalist Greece 2014 B
Panagiotis Kostopanagiotis infinity Greece 2013
Konstantinos Agiannis Greece No Participation
Emanuel Mihalainas Greece No Participation
Tanay Kothari Tanay1998 India No Participation
Malvika Raj Joshi a06 India 2014 S
Arjun P Superty India No Participation
Kushagra Juneja India No Participation
Muhammad Ayaz Dzulfikar azure97 Indonesia No Participation
Michael Wibawa M_W Indonesia No Participation
Agus Sentosa Hermawan aguss787 Indonesia No Participation
Stacia Edina Johanna Indonesia No Participation
Francesco Milizia fram Italy 2014 S
Marco Donadoni mark03 Italy No Participation
Filippo Baroni Delfad0r Italy No Participation
Peiman Jabbarzade JeBeK Iran No Participation
Ali Haghani Haghani Iran No Participation
Ali Bahjati alib Iran No Participation
Amir Keivan Mohtashami matrix Iran No Participation
Sami Daoud daoudsammy1 Jordan No Participation
Aleksejs Zajakins Alex_2oo8 Latvia 2014 S
Kristaps Čivkulis kristapuciitis Latvia 2014 S
Ingus Jānis Pretkalniņš Ingugugus Latvia 2014
Aleksejs Popovs popoffka Latvia 2011, 2012 B, 2013 B, 2014 S
Azret Kenzhaliev exm_kg Kyrgyzstan No Participation
Kadyrbek Narmamatov SEFI Kyrgyzstan 2014
Erkin Matkaziev Erkin97 Kyrgyzstan 2014
Zarlyk Jusubaliev heavenly_phoenix Kyrgyzstan No Participation
Kliment Serafimov Macedonia 2012 2013 2014 B
Hristijan Gjorshevski Macedonia No Participation
Mihail Denkovski Macedonia No Participation
Juan Carlos Sigler Priego Juanito98 Mexico No Participation
Carlos Galeana Hernandez charlyhlms Mexico No Participation
Angel David Ortega Ramirez blak_dragon Mexico No Participation
Emmanuel Antonio Cuevas EmmanuelAC Mexico No Participation
Marcel Bezdrighin yosei-san Moldova 2014
Mihail Tarigradschi thatmathguy Moldova No participation
Chihai Mihai mihai_chihai Moldova No participation
Motroi Valeriu Djok Moldova No participation
Dejan Todorovic zele.zeka Montenegro 2014
Velibor Dosljak nnMan Montenegro No Participation
Maciej Hołubowicz znirzejskwarka Poland No Participation
Jarosław Kwiecień rudy102 Poland 2014 G
Przemysław Jakub Kozłowski Poland No Participation
Konrad Jan Paluszek Poland No Participation
Gonçalo Paredes gonP Portugal 2014
José Correia jrcc Portugal No Participation
João Lago joaolago Portugal No Participation
Fábio Colaço fabioiuri Portugal No Participation
Hanpil Kang HYEA Republic of Korea No Participation
Jaehyun Koo koosaga Republic of Korea No Participation
Jeehak Yoon cubelover Republic of Korea 2014 G
Seunghyun Joe ainta Republic of Korea 2014 S
Alexandru Velea plus2CircletOfNobility Romania 2014 S
Rares Buhai rares.buhai Romania 2012 G, 2013 G, 2014 G
Andrei Popa AndreiNet Romania No Participation
Valentin Harsan valih10 Romania No Participation
Mikhail Ipatov LHiC Russia No participation
Vladislav Makeev overtroll Russia No participation
Mikhail Putilin SpyCheese Russia No participation
Nikolay Budin BudAlNik Russia No participation
Marko Stanković MeinKraft Serbia 2013 S, 2014 S
Dimitrije Erdeljan didins Serbia 2013 B, 2014 S
Dušan Živanović zDule98 Serbia No Participation
Nikola Jovanović randomusername Serbia No Participation
Teo Por Loong Singapore No Participation
Feng Jiahai Singapore 2014 G
Pang Wen Yuen pwypeanut Singapore No Participation
Howe Choong Yin Singapore No Participation
Eduard Batmendijn Baklazan Slovakia 2012 G, 2013 G, 2014 S
Bui Truc Lam Slovakia 2014 S
Pavel Madaj Slovakia No Participation
Samuel Sládek samo98 Slovakia No Participation
David Wärn Sweden No Participation
Aleksandar Abas Alex7 Syria 2014
Joud Zouzou joudzouzou Syria 2014
Besher Massri besher Syria No Participation
Mohammad Dwik dwik Syria No Participation
Pochang Chen johnchen902 Taiwan 2014 S
Po Jui Chen a00012025 Taiwan No Participation
Mekhrubon Turaev Ximera Tajikistan 2013,2014
Nodir Daminov Nodir.Daminov Tajikistan No Participation
Doro Umarov DARIUS_XIX Tajikistan 2013,2014
Suhaylii Bakhoduri Suhaylee Tajikistan No Participation
Muhammed İkbal Kazar ikbal Turkey No Participation
Muhammed Emin Ayar eminayar Turkey 2014 S
Abdullah Enes ÖNCÜ enesoncu Turkey 2014 B
Kayacan Vesek kayacanv Turkey No Participation
Bayram Berdiyev bayram Turkmenistan 2014
Silap Aliyev silap-aliyev Turkmenistan 2013 2014
Allanur Shiriyev allanur_tkm Turkmenistan No Participation
Gunesh Purchekov Turkmenistan No Participation
Moakher Mohamed moakhey Tunisia No Participation
Shevchenko Ilya Scorpy Ukraine 2013 B 2014 S
Aslandukov Matvey BigBag Ukraine No Participation
Kachur Roman Maestr0 Ukraine No Participation
Mikhno Mark CbI4 Ukraine No Participation
Rowan Lee Rowan.Lee United Kingdom No Participation
Daniel Chiu waterfalls USA No Participation
Demi Guo DemiGuo USA No Participation
Alexander Wei yummy USA No Participation
Andrew He ecnerwal USA 2014 G
Andrew Li ParanoidAndroid Uzbekistan No Participation
Raif Akhmedshin Zardos Uzbekistan No Participation
Abdulla Axmadaliyev a1549a Uzbekistan No Participation
Ulugbek Sobirov BEK97 Uzbekistan No Participation
Nguyen Tien Trung Kien kien_coi_1997 Vietnam 2014 B
Pham Van Hanh skyvn97 Vietnam No Participation
Nguyen Viet Dung Alpha_purple Vietnam No Participation
Phan Duc Nhat Minh minh141198 Vietnam No Participation

Please feel free to post the participants here too, so that there will be something to discuss :)

Congratulations! To those who qualified for IOI 2015 :)

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