Привет, Codeforces!
28 сентября 2015 года в 12:00 MSK состоится очередной раунд Codeforces #322 для участников из второго дивизиона. Традиционно, участники из первого дивизиона приглашаются поучаствовать в соревновании вне конкурса. Обратите внимание на необычное время начала раунда!
Этот раунд проводится по задачам школьного этапа Всероссийской олимпиады школьников по информатике 2015/2016 года г. Саратова. Задачи для вас готовил я и недавно вернувшийся из армии Эдвард Давтян (Edvard).
Хотелось бы сказать большое спасибо Максиму Ахмедову (Zlobober) за помощь в подготовке задач, Марии Беловой (Delinur) за перевод условий на английский, Михаилу Мирзаянову (MikeMirzayanov) за замечательные системы Codeforces и Polygon, а также Владимиру Петрову (vovuh) за прорешивание задач.
Участникам будет предложено шесть задач и два часа на их решение. Разбалловка будет объявлена позднее.
UPD Разбалловка задач 500-1000-1500-2000-3000-3000. Всем удачи!
UPD2 Разбор
UPD3 Поздравляем победителей!
Школьный этап для Саратовской области? А вообще супер fail, в 12:00 в понедельник это вообще не то время, а еще шесть задач приготовлены.
Соревнование проводится параллельно школьной олимпиаде, поэтому время необычное.
было много постов типа "Спортивное программирование и ...", поэтому в связи с новостью о твоем возвращении реквестирую пост "Спортивное программирование и армия". Не заставляли ли всем офицерам вирусы чистить и т.д. и .т.п. :). Интересно было бы почитать:)
Да этого треша хватало :-)
I think it'll be exciting to have one division combined contest per month.Is it possible?
Sure, you just have to provide problems for it.
That doesn't seem correct...
Also, the actual time seems to be just 2 hours before SRM 669...
Fixed.
Auto comment: topic has been updated by fcspartakm (previous revision, new revision, compare).
Ждём задачи про армию.
А как так получилось что вам пришлось служить или вы сами захотели?
В России после высшего образования заканчивается отсрочка о армии.. Судя по всему пришлось
А в России нет такого понятия как военная кафедра?
Она есть не везде. Не всем хочется ее проходить. Не всем удается на нее попасть. Не всем хочется не служить в армии.
Причин очень много.
Can you move it to Sunday afternoon please ? It is hard not just for me,but for many users to adapt to this unusual contest time...
4 AM in my part of the US o.O. At least I can participate.
It's in my school time :( !
OK i will take it virtual!
Why not just move the contest to Sunday at the usual time? This suspicious time seems like a move to try to "steal" contestants from Topcoder.
The competition is held parallel to the school competition, so the time is unusual.
What about moving your contest 15 minutes earlier? It's not a big change, but enough for a rest between CF round and SRM :D
What a perfect time for coders in East Asia! ( 5PM ~ 7PM )
nice idea :)
Solo 322 round.
Поставил против себя денег?:)
Ой, бросьте эти ваши шуточки, они неуместны. Вот если бы раунд был Div1 + Div2, и условия соответствующей тематики — тогда был бы вин. А так просто забейте.
Ставлю не на себя.
my school finish when contest is finished... :(
but my school finish when contest s finished.... :(
six problems and two hours ? Note that round starts in the unusual time ?
OMG very unusual contest :)
wtf?
QWQ 17:00 is good time ,but I have a class on Monday
you really that 17:00 is good time for you?
Can you add one problem and make it rated for both Div 1 & 2 :)
woooow nice idea
So I'm gonna skip school for this contest. Yay!
bad boy :)
i also skip my 'Chemistry'lesson beacuse of contest
We look forward to the classic problem of the Army. Good luck to all!
really?
Обидно, что этот контест не Bredor составлял...
6 problems in 2hrs. Imagining how easy/hard the problems will be. I have a hunch most Div2 will solve the C problem. The decider for remarkable rating changes might just be the D.
You can't predict it at all.. everything is possible in such competitive activities my dear :)
You can downvote all you want. You're basically wasting your time. :D
See more on KnowYourMeme!
Nothing has since changed in my life since the downvotes...well aside that am a few dollars richer. So keep up the downvotes and waste your precious time. :D :D :D
I don't understand how that could waste our time!? it literally takes one second to downvote a comment. :/
I actually don't expect you to understand how it would waste your time.
Just like you vote for political parties to form your government(if there's democracy in your country) to show whether you like them or not, you upvote/downvote without caring about the time you waste.
I wish the scoring will be IOI styled.
I wish that too.
I also wonder how's it 6 tasks for 2 hours, and Div. 2 contest. I thought the school stage of the Russian Olympiad would contain less but very hard problems. Let's hope for the problems to be useful for practicing by Olympiad participants! :D
Please test the system before starting time because SRM will begin after this contest directly
Is hacking allowed in this round? Since it is an unusual and parallel round, the confusion arises!
Yes.
very unusual contest ,i hope it has usual but interesting problems
Nooooooooo!! It had to happen just when my rating starts to rise a bit , Guess I've gotta wait for the next contest . Anyway I wish "ALL THE BEST" for those of you who participate .
Each contest you miss is your loss. Forget ratings. Ratings will rise when you become good and you can't become good by avoiding intimidating situations. I know this because I used to avoid contests too :)
Dude I cant miss my lab's either now , can I.....!! And what made you think that I was Avoiding It , when I was feeling bad that I wouldn't be participating in it....??I_love_Captain_America.
Так долго ждал этот раунд, а он див2. Feels bad man
слить хотел?
why this time??
Please CF be careful, any delays on this round will case it's intersection with TC round
12.00 Slightly unconvenient time for Ukraine.
Should we wait a long time for system testing and rating changes? I mean, maybe real competition won't finish at time we finish?
I really don't like the idea, that codeforces round finishes in the same moment when topcoder srm starts!
Does anyone know the way to influence topcoder administration?
ок :)
Why set a round in the unusual time? or Which case will lead a round in unusual time?
because it's something like mirror of school Olympiad, as far as I unserstood
Автокомментарий: текст был обновлен пользователем fcspartakm (предыдущая версия, новая версия, сравнить).
Good luck everyone! I will be doing this contest during lunch break at work! :D
100 bonus points to whoever wrote the ugliest solution to problem D?
http://ideone.com/exrBGb and even then failed the system tests :(
Absolute winner!!!!
I can't even ...
holy
mother of jesus christ!!!
Problem D was just horrible! (and to be serious it was a very good one :-) What is an elegant solution to this?
+1
It has too many conditions to handle. Curious to see if there's a recursive solution to it. I wrote a big messy solution , will submit it after system tests.
I doubt if there exists any elegant solution rather than dealing with each case possibly . However, it will be very nice if some red guy explains how they generally deal with these kinds of problems (don't they get irritated).
of course there is only two cases ! and these two cases are the ones in samples also it's easy to proof that only these cases might be correct ! check my solution : https://ideone.com/HomOtB
I used the following observation that there will always be atleast one rectange out of a, b & c whose one side will be equal to the side of the new square. It helped me a lot in concise my code.
Did this observation reduce your code length, or simply increase the number of conditions? The brute force way is a huge code, but at least its a complete copy paste work.
There are only 2 conditions:
If we'll
My submission: 13269637
Yours is neater than mine, and shorter.
I wrote solution, using straight forward idea:
1) try all 6 possible permutaions (3! = 6, 6 times call first function)
2) try all 8 possible swap's x and y (2 ** 3 = 8, 8 times call second function
Now you need to check only 2 possible answers.
Solution: 13270215
Can you explain why we need to take every permutation of the initial order? A counter-example would be perfect.
Try switching around the letters in the second example test and you will get different cases but if you take all permutations (or sort them like I did) it's only one case.
Мне контест не понравился тем, что первые четыре задачи были очень простыми (в C и D были очень простые), а E и F были очень сложные (особенно E), раз их решили 37 человек. И поэтому система была не очень честной из-за огромного различия в сложности между D и F.
В задаче D в претестах не было данных с ответом -1
Первые 4 супер изи, была всего лишь тупка над реализацией (откуда столько взломов????) А вот на последние 2 что-то до сих пор не придумал решение, хоть и условия простые :)
Can anyone tell me why my code gives me (and everywhere I checked ) right answer but gives wrong on system test? my solution: 13269100
I'm not sure is it the case, but
extremely inaccurate and is equal to
(if skill[i].rat is an integer variable) which is 100% accurate.
Что-то очень быстро рейтинги обновились. Как-то странно...
Unable to submit in practice mode. Please check.
The problems will be available after our onsite event completely ends. It seems it will be in 1 hour.
Будет ли городской этап ВОШ Саратовской области на Codeforces в выходной день?
Good round: good problems, fast system test, fast editorial. Problem F was very nice. Did anyone solved it in a different way to the editorial ?
В каком случае все попытки могут быть проигнорированы ?
I am not able to understand the solution presented in the editorial for the problem F. Can anybody explain me solution for problem F in a bit detail ?
new record :D
11 on div2 and new max
i wonder when i can re-submit some problem in this contest?
See MikeMirzayanov's comment :)
Problems were very interesting. so good... thanks for making this contest!!!
During contest I submitted a code , it passed pretest but got wa in system test .... now same code I submitted later and got accepted ..... what seems to be the problem here ...... :/ ....
code which got wa:
http://codeforces.me/contest/581/submission/13270251
same code which got ac later:
http://codeforces.me/contest/581/submission/13276903
Well. The problem is in this for:
for(int i = 0; (i < n) || (k > 0); i++)
When k is big, i becomes much more then n, so your progmam crashes and don't write anything (and get wa because of unexpected end of file). For example in test like: n = 10^5, k = 10^7, a[i] = 100.
I have no idea why it's passing tests now, but this is it.
P.S. Sorry for english.
Maybe it's features of codeforces, so after contest there is no problem with array index out of bounds.
If you increase the size of the array, the program works correctly.
hey thanks for taking your time and giving me replies :) ..... yes, it was a mistake.... and it's weird that it got accepted afterwards .....
На самой олимпиаде же не было последних 2х задач? Их из Дива2 то никто почти не решил)
К сожалению, были. И их, я так полагаю, решил в лучшем случае один человек
Задачи на оригинальном соревновании были проще. Во всех задачах ограничения были меньше. Например в задаче Е была только одна стартовая точка и она решалась намного проще.
А, действительно. Извиняюсь тогда, не читал условия из раунда, ожидал, что они аналогичны.
Но это не отменяет того, что почти никто их не решил
у победителя 5 полных баллов (одна из них предпоследняя) и 2 почти полных 55/60 и 57/60. Так что думаю сложность задач была выбрана достаточно удачно.
Ссылка на табличку есть?
Уже выложили.
Я про онсайт.