Nickolas's blog

April Fools Day Contest 2014
By Nickolas, 11 years ago, translation, In English

The contest is over; I hope you've enjoyed it :-) Editorial is here. See you next year!

The third April Fools Day Contest will take place on Tuesday April 1st. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is. Thanks to kit1980, Skiminok, Gerald and MikeMirzayanov for their help in preparing problems.

In this round you'll be given several weird problems (the estimated quantity is between 6 and 10) and 2 hours to solve them. The contest will use ACM ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them), and it will be unrated. You can submit solutions in any language allowed by Codeforces — well, unless the problem says otherwise :-)

Be warned, to enjoy competing in this round you'll need a sense of humor compatible with mine! Good luck, and have fun!

  • Vote: I like it
  • +370
  • Vote: I do not like it

Comments Comments (119)
| Write comment?
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +11 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +82 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +3 Vote: I do not like it

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:)

→ Reply
»
11 years ago, # |
  Vote: I like it +2 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +8 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it -19 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
← Rev. 2   Vote: I like it -8 Vote: I do not like it

Don't ignore it! You will regret :)

→ Reply
»
11 years ago, # |
  Vote: I like it -8 Vote: I do not like it

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

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

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

    → Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it -8 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
← Rev. 2   Vote: I like it -8 Vote: I do not like it

Are they fooling on the countdown page too?

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +17 Vote: I do not like it

    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 :-)

    → Reply
»
11 years ago, # |
← Rev. 2   Vote: I like it -32 Vote: I do not like it

→ Reply
»
11 years ago, # |
  Vote: I like it +5 Vote: I do not like it

2012 2013

→ Reply
»
11 years ago, # |
  Vote: I like it -6 Vote: I do not like it

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.

→ Reply
»
11 years ago, # |
  Vote: I like it -7 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +6 Vote: I do not like it

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

:D

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

no way to understand the problems exactly ><

→ Reply
»
11 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Stone, scissors, paper

→ Reply
»
11 years ago, # |
  Vote: I like it +2 Vote: I do not like it

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

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    you had to try send it many times

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    It was A + B

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    You just need to keep pushing :)

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    just give up

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Problem setters make mistakes in input data for samples! LOL

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

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

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        if a = 5 then 19

        else if a = 381 then 873

        else a + b

        Or I am just lucky when I submit this version!

        → Reply
        • »
          »
          »
          »
          »
          11 years ago, # ^ |
          ← Rev. 2   Vote: I like it -8 Vote: I do not like it

          My accept was converting int to string.

          	int a, b;
	cin >> a >> b;
	stringstream s;
	s << a + b;
	cout << s.str();
          → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it -9 Vote: I do not like it

    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)

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      That wasnt the crack.

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

      So true to the contest problem :)

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it -8 Vote: I do not like it

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

        → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      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 :)

      → Reply
  • »
    »
    11 years ago, # ^ |
    ← Rev. 2   Vote: I like it +28 Vote: I do not like it

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

    → Reply
  • »
    »
    11 years ago, # ^ |
    ← Rev. 2   Vote: I like it -11 Vote: I do not like it

    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. ^_^

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

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

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

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

        → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it -8 Vote: I do not like it

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

        → Reply
        • »
          »
          »
          »
          »
          11 years ago, # ^ |
            Vote: I like it +4 Vote: I do not like it

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

          → Reply
          • »
            »
            »
            »
            »
            »
            11 years ago, # ^ |
              Vote: I like it +8 Vote: I do not like it

            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

            → Reply
»
11 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Fortran, but which one?

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    FORTRAN 77

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

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

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

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

          603 FORMAT("FORTRAN 77")
   90 WRITE(6,603)
      STOP
      END
        → Reply
        • »
          »
          »
          »
          »
          11 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          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 ;)

          → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I did

        → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it +45 Vote: I do not like it

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

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +9 Vote: I do not like it

        The same question from my side.

        → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    77

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

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

    → Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What the hell was C?

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

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

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Fine, but how did everyone guess?

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        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.

        → Reply
        • »
          »
          »
          »
          »
          11 years ago, # ^ |
          ← Rev. 2   Vote: I like it 0 Vote: I do not like it

          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; } }

          → Reply
          • »
            »
            »
            »
            »
            »
            11 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

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

            → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        google translate or insight :D

        → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        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.

        → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

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

        → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        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..

        → Reply
        • »
          »
          »
          »
          »
          11 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Whoa :)

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

          → Reply
»
11 years ago, # |
  Vote: I like it +6 Vote: I do not like it

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

→ Reply
  • »
    »
    11 years ago, # ^ |
    ← Rev. 2   Vote: I like it +61 Vote: I do not like it

    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)

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

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

      → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      How did you realise it?

      → Reply
      • »
        »
        »
        »
        11 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

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

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

        → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

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

    → Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +25 Vote: I do not like it

Best contest ever

→ Reply
»
11 years ago, # |
← Rev. 2   Vote: I like it +2 Vote: I do not like it
→ Reply
»
11 years ago, # |
  Vote: I like it +20 Vote: I do not like it

Thank you very much for yet another fun contest!

→ Reply
»
11 years ago, # |
  Vote: I like it +45 Vote: I do not like it

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

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

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

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it +4 Vote: I do not like it

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

      → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

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

      → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      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

      → Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Loved it!!

Dont wanna wait another year for it :(

Great Work :)

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Contest was really funny enjoyed it :-)

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +8 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

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 :)

→ Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    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.)

    → Reply
  • »
    »
    11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    why is the answer 0101 in the last sample?

    → Reply
    • »
      »
      »
      11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      (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.

      → Reply
»
11 years ago, # |
  Vote: I like it +6 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What is the mystery of problem F?

→ Reply
»
11 years ago, # |
  Vote: I like it +8 Vote: I do not like it

i became an April fool today.

→ Reply
»
11 years ago, # |
  Vote: I like it +8 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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).

→ Reply
»
11 years ago, # |
  Vote: I like it +12 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it +11 Vote: I do not like it

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..... :)

→ Reply
»
11 years ago, # |
  Vote: I like it +5 Vote: I do not like it

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.

→ Reply
»
11 years ago, # |
  Vote: I like it -7 Vote: I do not like it

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

→ Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
  • »
    »
    11 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like 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.

    → Reply
»
11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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?

→ Reply