Первоапрельский контест 2014

№	Пользователь	Рейтинг
1	tourist	3985
2	jiangly	3814
3	jqdai0815	3682
4	Benq	3529
5	orzdevinwang	3526
6	ksun48	3517
7	Radewoosh	3410
8	hos.lyric	3399
9	ecnerwala	3392
9	Um_nik	3392

№	Пользователь	Вклад
1	cry	169
2	maomao90	162
2	Um_nik	162
4	atcoder_official	161
5	djm03178	158
6	-is-this-fft-	157
7	adamant	155
8	awoo	154
8	Dominater069	154
10	luogu_official	150

Контест окончен, надеюсь, вам понравилось :-) Разбор задач — здесь. До следующего года!

Во вторник 1 апреля состоится третий Первоапрельский контест — несерьезное соревнование, в котором решить задачу зачастую проще, чем догадаться, что же в ней надо сделать. В его подготовке мне помогали kit1980 и Skiminok, а также команда Codeforces в лице Gerald и MikeMirzayanov.

В этом раунде вас ждет несколько необычных задач (количество уточняется, по предварительным оценкам — от 6 до 10), на решение которых дается два часа. Раунд будет проводиться по схеме ACM ICPC (без взломов, положение в результатах определяется количеством решенных задач и набранным штрафным временем) и будет нерейтинговым. Решения можно сдавать на любом языке, поддерживаемом Codeforces — если, конечно, иное не оговорено в условии задачи :-) Чтобы получить представление о том, что вас ждет, можно взглянуть на контесты прошлых лет: 2012, 2013.

Как обычно, чувство юмора, совместимое с моим, является необходимым условием для успешного участия. Удачи!

Комментарии (157)

Показать архивные | Написать комментарий?

hball1st

11 лет назад, # |

← Rev. 4 →

-55

Судя по уровню авторов задачи будут несложными P.S. Извиняюсь, был неправ.

→ Ответить

EarlOfDitches

11 лет назад, # ^ |

+61

Не вижу в этом ничего страшного.

worse

+30

А мне норма =)

Nickolas

+28

Не скажу за других авторов, но лично я буду очень рада, если вы решите все задачи. Потому что в прошлом году это не удалось никому.

-8

Да, да, я извиняюсь, ляпнул не обдумав.

Nakochi

Sounds very interesting! I will play my fool part!2333 Enjoy the contest!

SAKT

+10

Best contest ever... Thanks Nickolas

mathlover

April Fools Day Contest is a fantastic contest~!!!! I believe all of coder can enjoy such an amazing contest!

yunfeng

Do you think so, now?

fpcsong

You are right!!!Very ~ interesting~!!!

TankEngineer

+11

Seems there will be more problems than last year. More probleams means more fun!

dht7166

this will be my first april fools contest, hope not too weird

antik

-22

Ай да авторы! Ай да хитрый 11 тест Див 2(С)

Ekaterina999

По-моему, вы немного перепутали и написали не туда =)

Death_Knight_DK

+82

I think it will be rated,because it's April fool's day~:)

lxw

that's right. I think too.~

chicken_coder

Haha, maybe we are too suspicious of it. :p

kien_coi_1997

-26

I think that it should be unrated.

Pancake

Death_Knight_DK is only joking.

I think Death_Knight_DK's sentence is right.

last_one

Sounds great!Hope not be a fool!QvQ And note "Be warned, to enjoy competing in this round you'll need a sense of humor compatible with mine!".I think it will be a happy day and rated:)

alohamaloha

Take a look at last years contest http://mirror.codeforces.com/contest/290 You will definitely participate after that :)

zscoder

I love April Fools Day Contest! Can't wait to try. :)

JuanMata

April Fool's Day surprise: contest will be rated :D

manetsus

-19

Do you want to see how accepted solution becomes wrong answer? Just visit the blog and enjoy! http://mirror.codeforces.com/blog/entry/11335 Everyone should keep it in mind who uses "w+"/"r+" in c++ for file handling. Do not be more fool!!

I_love_Coding

← Rev. 2 →

Don't ignore it! You will regret :)

ysymyth

Any statement will lose its reliability once it's about April Fool :)

zulkan

^this too, so, this is correct @_@

uc-nuts

not sure if there actually will be a contest or it's just another April fool.

courage

I think there will be a contest. You can find 2013's and 2012's

Kareem

Maybe there's no contest at all and that's just the trick haha :D

bli0042

April Fools Surprise: every problem is impossible to decipher and everyone ties :)

April Fools surprise: Every task is impossible and everyone ties. :)

Mr.Ers

-11

+42

В контестах по схеме ACM ICPC (без взломов) нет разделения участников на комнаты, поэтому опоздавшим ничего не мешает зарегистрироваться даже после начала контеста. В прошлые годы регистрацию продлевали до конца контеста по просьбам участников, в этом году решили сыграть на опережение :-)

+18

Завтра попробую с C начать решать. А то с Е не всегда получается...

Bekmyrat.A

Yay! good exams and good jokes :)

Elibay

-7

Почему будет не рейтинговым ??

veschii_nevstrui

Нехорошо давать рейтинг за задачи, в которых нет условия.

понятно

Robert.One

Why it wouldn't be rated? i thinks it will be interesting and you should make it rated:D, more people would participate

Or fewer people would participate because people value their rating more than a good laugh? You never know.

Personally I'd rather keep the round unrated with 1500 participants (last year's number) all having fun than make it rated, have unknown number of participants and have half of them complaining about losing rating on my idea of a joke :-)

shivshnkr

Are they fooling on the countdown page too?

+17

Are you referring to registration ending after contest start?

If a contest uses ACM ICPC rules (no hacks), there is no need to assign participants to rooms, so the latecomers don't have a problem registering after the contest start. In the past years we used to extend registration till the end of the contest per particilants requests, and this year we've decided to do it beforehand.

P.S. Funny how neither approach is a safeguard against questions about registration duration :-)

-32

KayacanV

2012 2013

davidlee1999WTK

-6

On the one hand, I hope the describtion of the problems is not very difficult for foreigners. On the other hand, the harder to understand the meaning of the problems, the more interesting the contest is.

Why it wouldn't be rated? I think there will be much participants if the contest is rated.

accidentallygivenfuck

No joke in Google homepage? Disappointed. But here is All of Google Jokes for April Fools' Day 2014. :)

Dixtosa

Before the end of the registration 02:02:22 Before the contest 00:02:22

anhldt

no way to understand the problems exactly ><

Kxzuir

= =

Shahzodbek

Stone, scissors, paper

jonathanirvings

I have to tilt my head to realize that "8<" is scissors. .__.

WictorT

It was realy hard to understand ! No idea how A+B may not be A+B .

aaaaaaaaaaaaaaaaaaaaaaab

you had to try send it many times

Golovanov399

It was A + B

cmd

You just need to keep pushing :)

pitfall

just give up

boleyn.su

Problem setters make mistakes in input data for samples! LOL

I just pushed writeln(a+b) and wrong answer at 1 test .

if a = 5 then 19

else if a = 381 then 873

else a + b

Or I am just lucky when I submit this version!

Barricadenick

My accept was converting int to string.

	int a, b;
	cin >> a >> b;
	stringstream s;
	s << a + b;
	cout << s.str();

-9

it is simply A+B, but u just have to shorten ur code a lot to get AC! :D
here is my solution 6212422 (after 5 WAs :P)

pulkit_180894

That wasnt the crack.

The thing was, keep submitting . After 5WA, it will get Accepted!

So true to the contest problem :)

lol, the first WA told me shorten the code. can't believe i actually did that 5 times!! :D

satchipear

Actually, it's not related to the code length. You only need to get 5 WAs first and then the AC will come. It's really an April Fools' gift :)

goryinyich

F..ck, I sent it 5 times and then gave up! On 6-th they were giving ACs! =(

SuprDewd

The trick was to not print a newline after printing out the sum. In Python, incorrect:

print(a+b)

Correct:

sys.stdout.write(a+b)

Edit: After noticing the "5WA" thing, I realised that this is probably not correct. ^_^

andreyv

Nope, it was not the trick. See above, you just had to keep submitting the same code.

Haha, just noticed... This is a very funny problem. x)

or, like me, believe the checker saying to shorten code and keep submitting different codes which produce same output A+B! :D

kennethsnow

The checker simply said "Looks really wrong to me.", not "Looks really long to me."

thanks, i misread that during contest!
but i guess that was good in a way, because i wouldn't have tried to reduce code length and resubmit! :D

MaxBuzz

Fortran, but which one?

enhydra

FORTRAN 77

pkacprzak

Did you print it without a default leading space character or not?

I’ve sent the following, based on an example from Wikipedia:

  603 FORMAT("FORTRAN 77")
   90 WRITE(6,603)
      STOP
      END

Darko

I sent the following (WA):

      program hello
          print *, "FORTRAN 95"
      end program hello

and this one (AC):

      program hello
          print *, "FORTRAN 77"
      end program hello

To be honest, I am not sure which one is correct ;)

vitux

I did

+45

Why the hell is it FORTRAN 77 while the compiler was gfortran95?

lisang

The same question from my side.

AlexSam

Yes, I also got this question here is my first submit — 6206074 and next a lot of submits just checked version for version :(

What the hell was C?

min(a[0],a[1],a[2]//2,a[3]//7,a[4]//4)

Fine, but how did everyone guess?

eduardische

You weren't given N, so one could guess that there are always 5 numbers. Then you're given a recipe with 5 items, so it was quite reasonable to try how many full products can you make given the quantities.

kofhearts

I thought you couldn't infer that since the following works without specifying the N. But, i should have tried anyway. :(

int main() { int temp; while(cin >> temp){ cout << temp << endl; } }

Usually doesn't happen with numbers on Codeforces — you're given N as well. Someone can correct me if I'm wrong though.

google translate or insight :D

nathanajah

Try google translate :)

It looks like a recipe, so I guessed that we will need 1 of the first element, 1 of the second element, 2 of the third element, 7 of the fourth element, and 4 of the last element to create one item.

Which implies we can create min(a[0],a[1],a[2]/2,a[3]/7,a[4]/4) item.

Lazzaro

Put the letter into Google Translator and you'll find it is written by Italian. And the key-point five numbers show up...

kumihimo

Copy & paste the code to google translate and then you can guess :) The rough idea is that every substance is formed by 5 elements, blablabla..

Whoa :)

I understood the recipe, but the “how many full items” part was obscure to me anyway.

kyuridenamida

I think that someone told people how to solve F around end. (Anyway, nice contest!)

Riatre

It's OEIS A000001. Couldn't tell why but this is the greatest (joke problem) idea I've ever seen :P

(After RUINING counting problems again and again, OEIS finally helped creating a great one LOL)

no wonder the problem name was 000001! :D
i thought it had something to do with binary representation! :D

Daydreamer

How did you realise it?

By OEISing the sequence in people's code after contest.

I have only failed submissions during contest. Wondering how people realize it too :-

+29

In desperation, I did a search with wildcards on OEIS looking for any sequences that matches the samples and noticed A000001 there by chance after trying few others.

sskolot

I was sure this task is something about binary representation...

Maybe, it was contrived intentionally.

First 1.5 hours : 2 AC Last 0.5 hours : 3 AC :O

+25

Best contest ever

Trytrytry

+22

Судя по топу, в Турции и Китае такие задачи решают каждый день:)

Не хотелось бы никого обвинять без каких-либо доказательств, но куча турков из одной организации засылающие F на последних минутах выглядит очень подозрительно.

AMendel

Раунд удался! Спасибо большое)

+20

Thank you very much for yet another fun contest!

G: Excel helped a lot :) http://imgur.com/iGdsj2A

I can't parse this word, can you explain me please?

chaotic_iak

5 + AVG Y. Basically average the y-coordinates, and add 5.

it's something (3 or 5 or S) +AVGY

flydutchman

It's "5 + A V G Y" which means that you just need to print out 5 plus the average value of y[] lol..I saw those graph during contest but cannot come up with that ideaQAQ

Loved it!!

Dont wanna wait another year for it :(

Great Work :)

Вывод в запуске на ввод x c Mysterious Language:

Can't compile file:
c:/programs/g95/all/../lib/gcc-lib/i686-pc-mingw32/4.1.2//libf95.a(main.o):(.text+0x32): undefined reference to `MAIN_'

Ответ на задачу B: Fortran 77, а не Fortran 95 :(

vogel

Как решалась F?

http://oeis.org/A000001

Te4NIK

OEIS A000001

princeladdak

Contest was really funny enjoyed it :-)

fake_delete_account

Best april fools day I have ever had) thx a lot

ahm.kam_92

We need April's Fool every month! It was very challenging and interesting :)

+44

Уважаемые авторы!

Знаете ли вы, что в Формуле-1 на данный момент было 64 сезона?!

minthe

Контест вынес мозг))

gamezovladislav

А потом занес обратно вперед ногами)

Jokser

In I-task I really thought that i need evaluate left part to zero and at the same time satisfy conditions from the right part. I was writing this task all contest time and finally i've just submit solution which only checks conditions and recovers minimal possible values. Surprisingly i've got AC :)

I guess you mean I. In that case, the third sample case breaks that hypothesis. (I also had the same thought until I evaluated the third sample case.)

PavelChadnov

why is the answer 0101 in the last sample?

(x) means x parentheses.

You need (3) to be greater than (2). Of course, you put (2) = 0 and (3) = 1. Now read the jaw: it spells (2), (3), (2), and (3) in order. So you feed the golorp with 0101.

Romchela

Расскажите, пожалуйста, D.

Получаешь порядковый номер факта — выводишь 1 если правда, 0 если нет.

Плюс всего 16 разных тестов с 2 возможными ответами на каждый, что означает, что можно "взолмать" задачу даже без использования гугла, просто перебирая ответы :)

Итого от 1 до 65к посылок. Теперь ясно, откуда в конце раунда появилась очередь)

← Rev. 3 →

Можно за log2(16) * 16 = 64 посылки.

Сначала определять тест, затем ответ на этот тест.

6225906 cant believe i was so close, but yet so far to solving B! :D

bor2com

Я получил приглашение на соревнование за 2.5 часа до начала. Пожалуйса высылайте приглашения заранее.

Kianoosh

What is the mystery of problem F?

M.Mahdi

OEIS.ORG

i became an April fool today.

Весёлый контест, спасибо!

Особенно позабавило то, что в F вроде как подходит формула $\text{[math]}$ , а 000001 намекает на что-то двоичное и соотносится с 64 = 2⁶.

а я думал что это минимальное x, такое, что 2^x>=n, по сэмплам подходило

u know the contest was unusual when u see that Petr made 11 wrong submissions on one problem and 22 wrong submissions on another (before, ofcourse, solving both in the end)! :D

Among all 27 people that solved 7 problems, they all miss two of F, G, I. Clearly these are the most difficult problems (D follows). Any one of them could have nabbed the first place by thinking more creative...

Amazing contest. I'm going to keep OEIS open in a tab for next year's contest. F successfully fooled me into thinking "floor of log2(x) — 1" and "floor of square root of x", especially after I figured out test 5 (1: 1) and test 6 (3: 1).

DanAlex

+12

For F: 000001 -> OEIS A000001 ... Seriously guys ? =)))))))))))

Классные задачи!!! Спасибо, Nickolas!!!

afrizal

I'm still wondering in D. Should I submit for every combination of 16 bytes?

No. Input N, output "1" if fact #N is true, "0" otherwise

EROR

Didn't get the solve for problem H A+B in the contest time.. :D I submit my solution five times and give up... i wish i would try only once more.. i would get Ac... :) Nice problem though.. We have a lot of fun..... :)

ahmed_aly

Again, I got the email announcing this contest 3 hours before the contest (at 5:30 AM in my time zone). Please next time send this email earlier.

so, when will the ratings be updated?
P.S. oops :D

is E straight forward math or is there a twist to it?

I found the page where the image came from but could not relate the values (e.g. 1.2, 3, 2). Just occurred to me that I did not even come close to exhausting the meaning of, for example, (1.2, 3, 2).

[EDIT] Forgot the link: http://mathworld.wolfram.com/SquarePyramid.html [/EDIT]

This contest is fun — it comes close to IPSC.

For the last problem, is the idea to choose values for the left side and make it minimal so that the right condition holds? I see there are several parts in the right side separated by comma which seems strange to me..is this a programming language specific thing?

kit1980

Please see the editorial: http://mirror.codeforces.com/blog/entry/11391?locale=en

Basically, golorp's name is a Prolog expression ("golorp" is "prolog" spelled backwards).

Блог пользователя Nickolas