Nickolas's blog

By Nickolas, 16 months ago, translation, In English,

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


The 6th April Fools Day Contest will take place on Sunday April 1st. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.

This year I tried to make the problems less puzzling and more versatile. For example, almost all problems have a statement! And you won't need OEIS this time :-)

In this round you'll be given 7 weird problems 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. To get an idea of what the contest will look like, you can check out the contests of the past years: 2012, 2013, 2014, 2016, 2017.

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

Announcement of April Fools Contest 2018
Announcement of April Fools Contest 2018
 
 
 
 
  • Vote: I like it
  • +490
  • Vote: I do not like it

»
16 months ago, # |
  Vote: I like it +83 Vote: I do not like it

Last time I had one problem solved; with OEIS problem gone, I wonder about my results now :v

»
16 months ago, # |
  Vote: I like it -69 Vote: I do not like it

I think one of the things this year will be that the contest will start an hour before or after (It will be a nice one).

  • »
    »
    16 months ago, # ^ |
      Vote: I like it -47 Vote: I do not like it

    I think there not gonna any such contest..They just made announcement to fool u all :P

    So don't waste ur time

»
16 months ago, # |
  Vote: I like it +128 Vote: I do not like it

»
16 months ago, # |
  Vote: I like it -176 Vote: I do not like it
  • »
    »
    16 months ago, # ^ |
    Rev. 3   Vote: I like it -43 Vote: I do not like it

    No.

  • »
    »
    16 months ago, # ^ |
      Vote: I like it -38 Vote: I do not like it

    Lol now you are going to get upvotes. Not because it was creative, because you are red coder.

    • »
      »
      »
      16 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      And you're wrong. How unsurprising.

      (I wrote that fully expecting to get downvoted, just to make the forced joke.)

      • »
        »
        »
        »
        16 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        They are downvoting you because of me. People do opposite to what I say. Guys can you upvote this comment? :)

  • »
    »
    16 months ago, # ^ |
      Vote: I like it +184 Vote: I do not like it

    A red getting downvotes? April fools came early this year.

  • »
    »
    16 months ago, # ^ |
      Vote: I like it -30 Vote: I do not like it

    Why don't you delete his comment Mike? You already deleted my comment. Is it because he is red?

    • »
      »
      »
      16 months ago, # ^ |
        Vote: I like it +16 Vote: I do not like it

      I'm sure you deleted your own comment.

      • »
        »
        »
        »
        16 months ago, # ^ |
          Vote: I like it -33 Vote: I do not like it

        You can't delete a comment 5 minutes after it is written mr.smart.

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

As you may probably know, there will be another similar April Fools Contest run by Indonesian coders: TOKI Open Contest Special — April Fools 2018 which will end 1 hour before Codeforces' contest start!

You may use this as an exercise tho, ;)

  • »
    »
    16 months ago, # ^ |
      Vote: I like it +36 Vote: I do not like it

    Additionally, there is a CodeFights Fools' Day Marathon which starts 25 minutes after the Codeforces special round and lasts for 90 minutes. So, one can solve April Fools' problems all day! Or night, depending on where on the globe you are at the moment.

»
16 months ago, # |
  Vote: I like it +18 Vote: I do not like it

I am Exited to be the fool by seeing the statement :D :D :D

»
16 months ago, # |
  Vote: I like it +83 Vote: I do not like it

"And you won't need OEIS this time."

April fool maybe! xD

»
16 months ago, # |
  Vote: I like it 0 Vote: I do not like it

April Fool : I'm not eligible for this Contest because My sense of humor is: !))%

»
16 months ago, # |
  Vote: I like it -20 Vote: I do not like it

"solving the problem is often easier than figuring out what the actual task is"

Codeforces Round #471 Problem B anyone?

  • »
    »
    16 months ago, # ^ |
      Vote: I like it +44 Vote: I do not like it

    I don't understand how did people not understand that problem... I think most people just didn't read the sentence "Check whether it can be split into two non-empty subsequences such that the strings formed by these subsequences are adorable.", or the sentence "Let's call a string adorable if its letters can be realigned in such a way that they form two consequent groups of equal symbols (note that different groups must contain different symbols)."

»
16 months ago, # |
  Vote: I like it -16 Vote: I do not like it

Well... What if there is not gonna be a contest because April fools :P

»
16 months ago, # |
Rev. 2   Vote: I like it -18 Vote: I do not like it

The 6th April Fools Day Contest will take place on Sunday April 1st.

No, April 1st is Saturday. :)

UPD: at least I didn't say "Monday" ...

»
16 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I like strange contest like this. Thanks to Nickolas

»
16 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I suddenly hate this time......I live in China,and that's at almost midnight.Also I will have to be in school!

»
16 months ago, # |
  Vote: I like it -7 Vote: I do not like it

Idk, but maybe there is 2+2=4-1=3 meme lol

»
16 months ago, # |
Rev. 4   Vote: I like it -31 Vote: I do not like it


The contest doesn't exist! Happy April fools' day!

»
16 months ago, # |
  Vote: I like it 0 Vote: I do not like it

excited ...

»
16 months ago, # |
  Vote: I like it -38 Vote: I do not like it

ONLY A FOOL WILL REGISTER THIS CONTEST OR NOT UPVOTE THIS COMMENT :P

  • »
    »
    16 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Who said Fool can't do cp...I found 19 fools here :|...Many others on the way

»
16 months ago, # |
  Vote: I like it 0 Vote: I do not like it

almost all problems have a statement??????That's Terribleeeee!

»
16 months ago, # |
Rev. 2   Vote: I like it +5 Vote: I do not like it

Is this UnRated isn't it?

By the way,in Japan,the contest will be held in April 2nd(00:35) lol

UPD:I didn't notice that a RedCoder ask the same question because it gets so many downvotes lol

»
16 months ago, # |
Rev. 3   Vote: I like it +17 Vote: I do not like it

Thank you Nickolas, for your contests, there are really interesting and unpredictable :D

»
16 months ago, # |
  Vote: I like it +5 Vote: I do not like it

You should increase contest duration.

»
16 months ago, # |
  Vote: I like it +9 Vote: I do not like it

Last year this contest made me mad... WTH, only input and output?... are you kidding me =)

»
16 months ago, # |
Rev. 4   Vote: I like it +25 Vote: I do not like it

Something will be strange in China...

the contest starts at 23:35 UTC+8, it means after half an hour, it's April 2nd.

Does it mean we should stop joking? Will we be able to see the original problem statement with out jokes?

Seems worse in Japan...

(Joking)

»
16 months ago, # |
  Vote: I like it +10 Vote: I do not like it

Can't wait for this contest, super hyped for the funny questions!

»
15 months ago, # |
  Vote: I like it +8 Vote: I do not like it

at the first sight i took this line for granted "This is a joke competition in which solving the problem is often easier than figuring out what the actual task is."but after going through previous contests ,i could really feel it..XD

»
15 months ago, # |
  Vote: I like it +17 Vote: I do not like it

the problem about April Fools Contest that we can't believe anything you say

you say we won't need OEIS this time this can mean that all the problems can be solved using OEIS

so it's complicated

»
15 months ago, # |
Rev. 2   Vote: I like it +1 Vote: I do not like it

Problems only have input and output?!!! i think that will be hard.

»
15 months ago, # |
  Vote: I like it +5 Vote: I do not like it

The joke this year is that the servers will go down during the contest.

Wait, isn't every contest an April Fools Day contest? Lol

»
15 months ago, # |
  Vote: I like it +3 Vote: I do not like it

sometimes unrated contests are also necessary ,we can think freely :D

»
15 months ago, # |
  Vote: I like it -12 Vote: I do not like it

Unrated or rated ? Beware you could become a Fool XD

»
15 months ago, # |
  Vote: I like it -53 Vote: I do not like it

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Can B be written in Java?

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    yeah.can written with any things..thinggggs

»
15 months ago, # |
  Vote: I like it -107 Vote: I do not like it

last problem of April Fools Day Contest 2018 : What's the difference between the two pictures above :? ^_______^

»
15 months ago, # |
  Vote: I like it +7 Vote: I do not like it

right from which you have evolved and left which helps you evolving ...

»
15 months ago, # |
Rev. 2   Vote: I like it +17 Vote: I do not like it

I think, Problem D can be solved using DP+LCA+Ternary-Search :)

  • »
    »
    15 months ago, # ^ |
    Rev. 4   Vote: I like it -63 Vote: I do not like it

    ;c

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +82 Vote: I do not like it

    Please don't give solution hints while the contest is still running. If this happens we'll have to make it unrated. Oh wait...

    • »
      »
      »
      15 months ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      According to the rating predictor I am gaining rating. Please don't make it unrated :P

    • »
      »
      »
      15 months ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      I think, according to --Someone--'s predictor he wasn't gaining rating, so he decided to make contest unrated. ;)

»
15 months ago, # |
Rev. 2   Vote: I like it +5 Vote: I do not like it

me in the contest XD

»
15 months ago, # |
  Vote: I like it +1 Vote: I do not like it

How to solve D?

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    I printed the word "black" and it passed.

    • »
      »
      »
      15 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      I passed with "2nd 12" (and didn't with "black" or "even") I guess, right answer changed time to time.

      • »
        »
        »
        »
        15 months ago, # ^ |
        Rev. 3   Vote: I like it 0 Vote: I do not like it

        I have printed "2" two times one time it gave me WA2 another time WA1. So the test cases were random.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    I bet on even.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It was random.

    I actually tested from 0, 00 to 36 looking for the answer.

    But it was to answer any of these "odd", "even". XD

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Printed 1st 12.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Try betting "Even" until random accepts it :D

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I printed 19 to 36

    1 to 18 failed

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    From the above comments I think that the system spins the roulette when you submit an answer.

»
15 months ago, # |
  Vote: I like it -37 Vote: I do not like it

»
15 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Let me hack D plz xD

»
15 months ago, # |
Rev. 2   Vote: I like it +5 Vote: I do not like it

I`m Unlucky :( are you lucky :P help me to become lucky :D :D

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Can anyone help me in Problem D, I don't know how to do, but I found test 1 change from 3,10,13,36.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Its completely random since its a gamble, I just printed "even" and it worked on my 4th submission

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Just bet anything you like. If you win the bet, you get accepted. So just keep submitting something like print('Odd') until you win.

»
15 months ago, # |
Rev. 2   Vote: I like it +6 Vote: I do not like it

F — 3 sample:

'-' = 45, '1' = 49, '2' = 50 ect. (ASCI)

112 = ( 49 * 10 + 49 ) * 10 + 50 = 5440

-37 = ( 45 * 10 + 51 ) * 10 + 55 = 5065

5440 - 5065 = 375

But how to decide the rest I did not understand...

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    The author of the reference solution, while decoding ascii strings to numbers, accidentally added the plus/minus characters to the next number. Note that to determine the value of a digit, you subtract '0' (=48) from it.

    2+2 = ('2'-'0') + ('+'-'0')*10 + ('2'-'0') = 2 + (-5)*10 + 2 = -46
    

    The rest follow similarly.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    112 = (('1' - '0') * 10 + '1' - '0') * 10 + '2' - '0' = 112

    -37 = (('-' - '0') * 10 + '3' - '0') * 10 + '7' - '0' = -263

    112 - -263 = 375

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve Problem D ?

»
15 months ago, # |
  Vote: I like it +3 Vote: I do not like it

How to solve E ?

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Count hard and soft. Chessboard alternates color black, white. Find smallest size square chessboard such that we may place all hard in one color, and soft in the other.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    You are supposed to print out the size of the smallest square chess board that could fit the cheeses if you put hard cheeses on one color of squares and soft cheeses on the other color.

»
15 months ago, # |
  Vote: I like it +1 Vote: I do not like it

How to solve B?

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Once you're certain what type of cat you're dealing with, output "normal" or "grumpy" to standard out.
    You have to print the answer as soon as possible

  • »
    »
    15 months ago, # ^ |
    Rev. 2   Vote: I like it 0 Vote: I do not like it

    check on if "no way", "go die in a hole", "are you serious?", "worse", "terrible".

    the number of checks is not more than 6

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Scan to see if the string given is "no", if not then check to see if the string is one of the "good" cat areas: great, don't think so, don't touch me, not bad, cool. If it is a normal location, return "normal". Then do an else if and check for the bad locations: are you serious?, no way, go die in a hole, worse, don't even, terrible. If it is a bad location, return "grumpy".

  • »
    »
    15 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Just follow the problem description. It's clear enough and you don't need to guess anything.

    • »
      »
      »
      15 months ago, # ^ |
      Rev. 2   Vote: I like it 0 Vote: I do not like it

      :/ ummm I think not, considering that the point of the contest is to give problem statements that you have to guess at

»
15 months ago, # |
  Vote: I like it +3 Vote: I do not like it

How to solve H?

  • »
    »
    15 months ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    It's quite easy. To get an AC, you don't need to print anything!

»
15 months ago, # |
  Vote: I like it +29 Vote: I do not like it

Lol??

»
15 months ago, # |
  Vote: I like it +5 Vote: I do not like it

Why there was no 'Runtime Error' verdict in problem B? I used asserts but it resulted in WA. I spent ~40 minutes to figure it out.

And how exactly did the input in this problem look? I used asserts to check that the given string is one of the strings from the statement, but it didn't pass so I had to remove them to accept the problem.

  • »
    »
    15 months ago, # ^ |
      Vote: I like it -16 Vote: I do not like it

    In B, you must output the type of cat as soon as you figure out what type of cat it is.

    • »
      »
      »
      15 months ago, # ^ |
        Vote: I like it +16 Vote: I do not like it

      I know, but it doesn't answer the question why the code

      int main() {
          assert(false);
      }
      

      gets WA and not RE.

      • »
        »
        »
        »
        15 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Hmm, that's interesting... does codeforces ignore asserts, maybe?

        • »
          »
          »
          »
          »
          15 months ago, # ^ |
            Vote: I like it +8 Vote: I do not like it

          Hey man, it's not my first contest on Codeforces :) They work in other problems. Maybe it is specific behaviour for interactive problems, though I haven't ever seen such thing before.

      • »
        »
        »
        »
        15 months ago, # ^ |
          Vote: I like it +6 Vote: I do not like it

        Maybe this is also a part of the April Fool... :P

»
15 months ago, # |
  Vote: I like it +7 Vote: I do not like it

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

In B, I was getting WA checking only given words. Then added "normal" and "grumpy" in the list. Guess what? LOL :p

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

For problem B, I just tried random and it works magic http://codeforces.com/contest/952/submission/36819128.

»
15 months ago, # |
  Vote: I like it +18 Vote: I do not like it

Oh... Although guessing statements is indeed interesting, I prefer problems with complete statements such as B,C and G. Cost a lot of time guessing statements of E and F but didn't solve any one. ╮(╯-╰)╭

»
15 months ago, # |
  Vote: I like it +11 Vote: I do not like it

Is it coincidence that if you use google's I'm feeling lucky on "I'm feeling lucky" you'll see a roulette??

https://www.lifewire.com/im-feeling-lucky-button-1616813

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve F?

»
15 months ago, # |
  Vote: I like it +22 Vote: I do not like it

I shed tears after I finally knew the truth of D

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

When you got a bug in E and thought that you got the statement wrong...

»
15 months ago, # |
Rev. 2   Vote: I like it -10 Vote: I do not like it

Problem D was like a hell, I tried 1~36, and "even"/"odd", and many type of "chip in a square" patterns :)

---

|O|

or

===

|0|

or

100,9,25 square of number or

"sqrt(100)" <-- this is still a chip in square * * * Finally, the answer was "Red"...

»
15 months ago, # |
  Vote: I like it -10 Vote: I do not like it

Is it rated??

»
15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hi Codeforces community... I was wondering why this contest is not listed in my Contest history ?

Regards!

»
15 months ago, # |
Rev. 3   Vote: I like it 0 Vote: I do not like it

Awesome!