Nickolas's blog

April Fools Day Contest 2013
By Nickolas, 12 years ago, translation, In English

The contest editorial is available here.

Some jokes are fun only for the first time, repeating them makes them lose their charm. I certainly hope that April Fools Day Contest is not the case, but there's only one way to verify this :-) I'm happy to invite you to take part in the verification process which will take place on Monday April 1st. Let me disprove the suspicions some people have: the joke is the contest contents, not the fact of its existence or the lack of it — that would have been too simple :-)

In this round you'll face several weird problems and 2 hours to solve them. The contest will be unrated (you bet!), and it will follow ACM ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces. To get an idea of what awaits you, you can have a look at the last year's contest.

Be warned, to enjoy participation in this round you'll need a sense of humor compatible with mine! It's April Fools Day, after all. Good luck!

Upd. Registration is open till the end of the contest.

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

Comments Comments (96)
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12 years ago, # |
  Vote: I like it +34 Vote: I do not like it

I love this kind of contests. Eagerly waiting for it ;)

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12 years ago, # |
← Rev. 2   Vote: I like it -59 Vote: I do not like it

Funniest April fool contest would be to have no contest at all :P EDIT: Instead of funniest , I should have written Scariest.

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    12 years ago, # ^ |
      Vote: I like it +26 Vote: I do not like it

    Let me disprove the suspicions some people have: the joke is the contest contents, not the fact of its existence or the lack of it — that would have been too simple :-)

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12 years ago, # |
  Vote: I like it +5 Vote: I do not like it

At what time will it start?

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12 years ago, # |
  Vote: I like it +35 Vote: I do not like it

“The contest will be unrated (you bet!)”

Isn't it a trick?I wonder...

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    12 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    I think it is not. (last year's this contest was unrated.)

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      12 years ago, # ^ |
        Vote: I like it +11 Vote: I do not like it

      Maybe this year they've decided to play trick on us this way

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        12 years ago, # ^ |
          Vote: I like it -11 Vote: I do not like it

        I don't think so,

        because the rules of contest is different from CF rounds, it's ACM rules.

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          12 years ago, # ^ |
          ← Rev. 2   Vote: I like it +9 Vote: I do not like it

          There are some contests which were held with using ACM's rules, which are rated contests.

          For example, this. http://codeforces.net/contest/240

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          12 years ago, # ^ |
            Vote: I like it +5 Vote: I do not like it

          You are so careful...But I think they'll have ways to rate it if they really want...

          All in all,what I said is also a trick.Happy April Fools Day!

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    12 years ago, # ^ |
    ← Rev. 2   Vote: I like it +7 Vote: I do not like it

    i think it isn't a trick because this is different from other contest

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12 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Last Year there were no pretests , every solutions that were submitted got accepted ... felling fooled again remembering the funny day a year back ... God knows what surprize is waiting today :)

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    12 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Not only God knows that today's contest will follow ACM ICPC rules; therefore — there'll be no pretests :)

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12 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Thank you very much for preparing these matches like special-language & April fools ! Great game I can't love it more! Hope you can preparing more for us. Geeks ! Let's have fun , and good luck!

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12 years ago, # |
  Vote: I like it +12 Vote: I do not like it

yeah, i will go RED today :D :)

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    12 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Wish you will be a grey today! You know i don't mean it. If this is rated wish you will be successful. If this is not then hope you will be red soon :D

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      12 years ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      Yeah, grey is quite good for april fool :) :p

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12 years ago, # |
  Vote: I like it -34 Vote: I do not like it

i hate April fool....

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12 years ago, # |
  Vote: I like it +30 Vote: I do not like it

I very expect the weird problems! :D

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12 years ago, # |
  Vote: I like it +26 Vote: I do not like it

This will be my birthday celebration contest :D Not to be fooled. 1st April is really my birthday :D I'm eagerly waiting for this contest.

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    12 years ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    So.. wish you a bad birthday? Aha, you know what I mean. Let's enjoy the contest anyway.

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      12 years ago, # ^ |
        Vote: I like it +15 Vote: I do not like it

      And I won't give you thanks bro. I've already given it.

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    12 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Wish u many happy returns of this day in codeforces :)

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12 years ago, # |
  Vote: I like it +14 Vote: I do not like it

An only disappointing thing is this contest will be held on April 2 in Japan...(a matter of timezone)

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

It should be very interesting as I think. Good luck!

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12 years ago, # |
  Vote: I like it -23 Vote: I do not like it

last ten minute

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12 years ago, # |
← Rev. 2   Vote: I like it +3 Vote: I do not like it

Last year's problem A:

The input contains two integers a1, a2 (0 ≤ ai ≤ 109), separated by a single space.

It's nice.

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12 years ago, # |
  Vote: I like it -13 Vote: I do not like it

cannot access the competition for the past 40 minutes. There is some issue. Moderators please look into it.

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12 years ago, # |
← Rev. 4   Vote: I like it +5 Vote: I do not like it

This is how Google makes people April Fools :

Google NoseBeta


Edit : Those who still think it is real are downvoting ?! :D
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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I am unable to register after the start of the contest :(

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

it is harder than last year . i didnt solve a problem ! :( . i guess today is just not my day !

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12 years ago, # |
  Vote: I like it +4 Vote: I do not like it

It make me crazy,but it is very fun!On the other hand,I think I should learning more American history:)

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12 years ago, # |
  Vote: I like it -20 Vote: I do not like it

So, I gues, HQ — (amount of(H) * 11 + amount of(Q) * string.length) % 2 == 0(Yes) else (No)?

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    12 years ago, # ^ |
      Vote: I like it -10 Vote: I do not like it

    I think, it's equal to amount of(H) % 2 == (amount of(Q) * string.length) % 2 ? "Yes" : "No"

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    12 years ago, # ^ |
      Vote: I like it +14 Vote: I do not like it

    From what I found, answer actually depends on order of letters, not just number of them, as for test 4 (HHQQHHQQHH) answer is "Yes", but for test 7 (HHQHQQQHHH) answer is "No".

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    12 years ago, # ^ |
    ← Rev. 2   Vote: I like it +23 Vote: I do not like it

    Can you all please not post your guesses (which everyone did by themselves in a large amount) and post actual solutions if you have AC or any useful observations? Please?

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12 years ago, # |
  Vote: I like it +26 Vote: I do not like it

Thanks God It Was unrated :P :D

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12 years ago, # |
  Vote: I like it +14 Vote: I do not like it

I'm dying to know what was the idea behind the HQ9+ problem !

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    12 years ago, # ^ |
    ← Rev. 2   Vote: I like it -8 Vote: I do not like it

    I think: H-prints H. Q-prints reversed source code. question: do we have a valid output of some code?

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12 years ago, # |
  Vote: I like it +30 Vote: I do not like it

I never really liked raccoons...

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Fantastic and super fun contest! :)

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12 years ago, # |
  Vote: I like it +24 Vote: I do not like it

We want F's sulotion, please.:D

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12 years ago, # |
  Vote: I like it +3 Vote: I do not like it

That was very cool and fantastic contest!!! I hope we have much more contests like this!! Thnx Problemsetter!

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12 years ago, # |
  Vote: I like it +59 Vote: I do not like it

When I got WA 40 on F and got 1 hour left, I thought I got it... Then one hour trying with so much pain T_T

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    12 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    There are 45 tests in this problem.

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    12 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I try to run a algorithm to get Hamiltonian Circle and got on WA 40 too..

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      12 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      How did you solve it in the contest?I wrote DP, but I got WA on test 4.

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

nightmare....TAT...

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12 years ago, # |
← Rev. 3   Vote: I like it +1 Vote: I do not like it

only 1 participant solve problem F :O WTF

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12 years ago, # |
← Rev. 3   Vote: I like it +9 Vote: I do not like it

Really amazing contest! AWESOME ! Never competed in such type of contests before.

What is the solution for A ( I couldn't figure it out and I cannot wait for the Solve Page ) ?

At B I copied the QR image and converted it into a matrix of 0s and 1s. But i tend to think that the solution was (x xor y) % 2 or ((x-1) xor (y-1)) % 2 .

Problems C and D were already solved. (in the statement)

I have no idea for E and F, but surely HQ9+ is a joke.

Great Job! Awesome Contest!

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12 years ago, # |
  Vote: I like it -11 Vote: I do not like it

When rating updates?

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12 years ago, # |
← Rev. 2   Vote: I like it +7 Vote: I do not like it

I'm curious that how to get all the 40 names for problem A just within 2 or 3 minutes.

For problem B, did you generate the 0-1 array with the help of some tool?

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    12 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You can search them in Google.

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      12 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it

      Of course, but after googling, the first page contains some formatted list of names, such as the following:

      1. George Washington, 1789-1797

      2. John Adams, 1797-1801

      3. Thomas Jefferson, 1801-1809

      4. James Madison, 1809-1817

      ...

      Then some text processing work has to be done which cost minutes.

      It seems that Wikipedia doesn't have a clear name-ONLY list either.

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        12 years ago, # ^ |
          Vote: I like it -10 Vote: I do not like it

        Orly?

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        12 years ago, # ^ |
        ← Rev. 2   Vote: I like it +1 Vote: I do not like it 
        import re
a = '''
[paste here]
'''
print '{'+str(re.findall('(\w+),',a)).replace('\'','"')[1:-1]+'}'

        It is not hard to parse the list if you know Python.

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        12 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I actually typed all of them in 3 minutes.

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        12 years ago, # ^ |
        ← Rev. 5   Vote: I like it 0 Vote: I do not like it

        You should use text editor which supports regex text search & replace. It should solve the problem instantly, e.g. replace (.*)\n with "$1",\n

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    12 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    there are online QR code decoders that will convert the QR code image into strings of 0 and 1 :)

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12 years ago, # |
← Rev. 2   Vote: I like it +83 Vote: I do not like it

The "problem" to problem E: Given that

input H -> output H
input Q -> output source code

Determine if the input sequence is a possible output of some HQ program.

The "solution" for problem F seems to be a greedy algorithm, walk to the point with smallest degree each time.

I figure these out by reading the AC code of others :P. Anyway, nice contest :D.

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12 years ago, # |
← Rev. 4   Vote: I like it +44 Vote: I do not like it

Wow Great Contest I really liked how havaliza was solving problem F if you see his submissions the test that is getting WA is increasing. he hashes the problem and tests it with Yes and No and to get the hash number he creates an array with hash number size. so when the program terminates he understands the hash number. kinda like hacking :D

If he only had a little more time...

his last submission : 3449579

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    12 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    wow!

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    12 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    Can u please explain how did he get hash after making array. The memory usage gives the maximum mem usage among all the cases, so what else it can be? Like when I submitted his soln, all I get to know is a WA on tc 39. Any hints?

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      12 years ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      he would only create an array on the last case. if you see his code he has used exit(0) on the determined test cases so that the code would not make an array on those tests.

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12 years ago, # |
  Vote: I like it +9 Vote: I do not like it

System Testing here ?? fooling continues .

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

The problems were awesome,though I could solve only C and D. A was also easy,but I could not get the logic because my GK is not that good.

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12 years ago, # |
  Vote: I like it -13 Vote: I do not like it

Interesting!! Look at the toppest user!

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Excuse me please, I'm wondering why today's problems don't support practice after contest? Will this measure be canceled later?

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12 years ago, # |
  Vote: I like it +2 Vote: I do not like it

Best April Fools Picture for me!

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12 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Wow. Great Contest and Very attractive ideas for problem. specially 290A - Mysterious strings, I enjoyed it. it was harder than last year :D

for problem E :

H --> Prints "Hello, world!".

Q --> Prints the entire text of the source code file.

9 --> Prints the complete canonical lyrics to "99 Bottles of Beer on the Wall".

Plus(+) --> Increments the accumulator.

Be More successful. :)

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12 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

How I'd solve problem E (I didn't solve it during the contest, because I didn't get what was the task :D):

  • realize that if there're q letters 'Q' in the original program, then there must be q^2 letters 'Q' in the output

  • next, if there are h_0 letters 'H' before the first 'Q' in the program, there must be 2h_0 letters 'H' and a 'Q' after that, in the output

  • if there are h letters 'H' in the program, then there must be h(q+1) letters 'H' in the output

So it's possible to extract the first quine printed easily (it has length h+q and starts with the h_0+1st letter, in the output), and then simulate its output and compare it to the input.

Code: 3450396

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12 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Great and interesting problems. Really enjoyed the contest. :D

I LOVE MONGOLIA || Би Монголдоо хайртай

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12 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Please open practice .

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12 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Had to work :( Interesting that no red coder was in the top 5!

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12 years ago, # |
  Vote: I like it +16 Vote: I do not like it

This contest was awesome!

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12 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Will there be an editorial for this contest?

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12 years ago, # |
  Vote: I like it +4 Vote: I do not like it

nice contest :)

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12 years ago, # |
  Vote: I like it +9 Vote: I do not like it

i have never seen this type of problem in contest, anyway the problems were challenging..

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