### Nickolas's blog

By Nickolas, 4 years ago, translation,

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

• +490

 » 4 years ago, # |   +83 Last time I had one problem solved; with OEIS problem gone, I wonder about my results now :v
 » 4 years ago, # |   -69 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).
•  » » 4 years ago, # ^ |   -47 I think there not gonna any such contest..They just made announcement to fool u all :PSo don't waste ur time
 » 4 years ago, # |   +128
•  » » 4 years ago, # ^ |   -10
 » 4 years ago, # |   -176
•  » » 4 years ago, # ^ | ← Rev. 3 →   -43 No.
•  » » 4 years ago, # ^ |   -38 Lol now you are going to get upvotes. Not because it was creative, because you are red coder.
•  » » » 4 years ago, # ^ |   0 And you're wrong. How unsurprising. (I wrote that fully expecting to get downvoted, just to make the forced joke.)
•  » » » » 4 years ago, # ^ |   0 They are downvoting you because of me. People do opposite to what I say. Guys can you upvote this comment? :)
•  » » 4 years ago, # ^ |   +184 A red getting downvotes? April fools came early this year.
•  » » 4 years ago, # ^ |   -30 Why don't you delete his comment Mike? You already deleted my comment. Is it because he is red?
•  » » » 4 years ago, # ^ |   +16 I'm sure you deleted your own comment.
•  » » » » 4 years ago, # ^ |   -33 You can't delete a comment 5 minutes after it is written mr.smart.
 » 4 years ago, # |   +12 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, ;)
•  » » 4 years ago, # ^ |   +36 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.
 » 4 years ago, # |   +18 I am Exited to be the fool by seeing the statement :D :D :D
 » 4 years ago, # |   +83 "And you won't need OEIS this time."April fool maybe! xD
 » 4 years ago, # |   0 April Fool : I'm not eligible for this Contest because My sense of humor is: !))%
 » 4 years ago, # |   -20 "solving the problem is often easier than figuring out what the actual task is"Codeforces Round #471 Problem B anyone?
•  » » 4 years ago, # ^ |   +44 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)."
 » 4 years ago, # |   -16 Well... What if there is not gonna be a contest because April fools :P
•  » » 4 years ago, # ^ |   0
 » 4 years ago, # | ← Rev. 2 →   -18 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" ...
 » 4 years ago, # |   0 I like strange contest like this. Thanks to Nickolas
 » 4 years ago, # |   0 I suddenly hate this time......I live in China,and that's at almost midnight.Also I will have to be in school!
 » 4 years ago, # |   -7 Idk, but maybe there is 2+2=4-1=3 meme lol
 » 4 years ago, # | ← Rev. 4 →   -31 The contest doesn't exist! Happy April fools' day!
 » 4 years ago, # |   0 excited ...
 » 4 years ago, # |   -38 ONLY A FOOL WILL REGISTER THIS CONTEST OR NOT UPVOTE THIS COMMENT :P
•  » » 4 years ago, # ^ |   0 Who said Fool can't do cp...I found 19 fools here :|...Many others on the way
 » 4 years ago, # |   0 almost all problems have a statement??????That's Terribleeeee!
 » 4 years ago, # | ← Rev. 2 →   +5 Is this UnRated isn't it?By the way,in Japan,the contest will be held in April 2nd(00:35) lolUPD:I didn't notice that a RedCoder ask the same question because it gets so many downvotes lol
 » 4 years ago, # | ← Rev. 3 →   +17 Thank you Nickolas, for your contests, there are really interesting and unpredictable :D
 » 4 years ago, # |   +5 You should increase contest duration.
 » 4 years ago, # |   +9 Last year this contest made me mad... WTH, only input and output?... are you kidding me =)
 » 4 years ago, # | ← Rev. 4 →   +25 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)
 » 4 years ago, # |   +10 Can't wait for this contest, super hyped for the funny questions!
 » 4 years ago, # |   +8 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
 » 4 years ago, # |   +17 the problem about April Fools Contest that we can't believe anything you sayyou say we won't need OEIS this time this can mean that all the problems can be solved using OEISso it's complicated
 » 4 years ago, # | ← Rev. 2 →   +1 Problems only have input and output?!!! i think that will be hard.
 » 4 years ago, # |   +5 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
 » 4 years ago, # |   +3 sometimes unrated contests are also necessary ,we can think freely :D
 » 4 years ago, # |   -12 Unrated or rated ? Beware you could become a Fool XD
 » 4 years ago, # |   -53
 » 4 years ago, # |   0 Can B be written in Java?
•  » » 4 years ago, # ^ |   0 yeah.can written with any things..thinggggs
 » 4 years ago, # |   -107 last problem of April Fools Day Contest 2018 : What's the difference between the two pictures above :? ^_______^
 » 4 years ago, # |   +7 right from which you have evolved and left which helps you evolving ...
 » 4 years ago, # | ← Rev. 2 →   +17 I think, Problem D can be solved using DP+LCA+Ternary-Search :)
•  » » 4 years ago, # ^ | ← Rev. 4 →   -63 ;c
•  » » » 4 years ago, # ^ |   +3 You know you somehow leaked out the solution lol
•  » » 4 years ago, # ^ |   +82 Please don't give solution hints while the contest is still running. If this happens we'll have to make it unrated. Oh wait...
•  » » » 4 years ago, # ^ |   +2 According to the rating predictor I am gaining rating. Please don't make it unrated :P
•  » » » 4 years ago, # ^ |   +1 I think, according to TheDramaQueen's predictor he wasn't gaining rating, so he decided to make contest unrated. ;)
 » 4 years ago, # | ← Rev. 2 →   +5 me in the contest XD
 » 4 years ago, # |   +1 How to solve D?
•  » » 4 years ago, # ^ |   +4 I printed the word "black" and it passed.
•  » » » 4 years ago, # ^ |   0 I passed with "2nd 12" (and didn't with "black" or "even") I guess, right answer changed time to time.
•  » » » » 4 years ago, # ^ | ← Rev. 3 →   0 I have printed "2" two times one time it gave me WA2 another time WA1. So the test cases were random.
•  » » 4 years ago, # ^ |   +4 I bet on even.
•  » » 4 years ago, # ^ |   0 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
•  » » 4 years ago, # ^ |   0 Printed 1st 12.
•  » » 4 years ago, # ^ |   0 Try betting "Even" until random accepts it :D
•  » » 4 years ago, # ^ |   0 I printed 19 to 361 to 18 failed
•  » » 4 years ago, # ^ |   0 From the above comments I think that the system spins the roulette when you submit an answer.
 » 4 years ago, # |   -37
 » 4 years ago, # |   +4 Let me hack D plz xD
 » 4 years ago, # | ← Rev. 2 →   +5 Im Unlucky :( are you lucky :P help me to become lucky :D :D
 » 4 years ago, # |   0 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.
•  » » 4 years ago, # ^ |   0 Its completely random since its a gamble, I just printed "even" and it worked on my 4th submission
•  » » 4 years ago, # ^ |   0 Just bet anything you like. If you win the bet, you get accepted. So just keep submitting something like print('Odd') until you win.
 » 4 years ago, # | ← Rev. 2 →   +6 F — 3 sample:'-' = 45, '1' = 49, '2' = 50 ect. (ASCI)112 = ( 49 * 10 + 49 ) * 10 + 50 = 5440-37 = ( 45 * 10 + 51 ) * 10 + 55 = 50655440 - 5065 = 375But how to decide the rest I did not understand...
•  » » 4 years ago, # ^ |   +15 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.
•  » » 4 years ago, # ^ |   +10 112 = (('1' - '0') * 10 + '1' - '0') * 10 + '2' - '0' = 112-37 = (('-' - '0') * 10 + '3' - '0') * 10 + '7' - '0' = -263112 - -263 = 375
•  » » » 4 years ago, # ^ |   0 Well, okay...)
 » 4 years ago, # |   0 How to solve Problem D ?
•  » » 4 years ago, # ^ |   +1 You just have to print "black" or "even" and be lucky
•  » » 4 years ago, # ^ |   0 I printed "Odd" and get AC
 » 4 years ago, # |   +3 How to solve E ?
•  » » 4 years ago, # ^ |   +3 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.
•  » » 4 years ago, # ^ |   +3 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.
•  » » » 4 years ago, # ^ |   +1 -___-I had this idea but decided to count the number of 'm' in input instead
 » 4 years ago, # |   +1 How to solve B?
•  » » 4 years ago, # ^ |   0 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
•  » » » 4 years ago, # ^ |   0 I always did 6 checks (from 0 to 5)
•  » » » » 4 years ago, # ^ |   0 You can sometimes do it in one, eg if you see 'no way' then it must be a grumpy cat
•  » » 4 years ago, # ^ | ← Rev. 2 →   0 check on if "no way", "go die in a hole", "are you serious?", "worse", "terrible".the number of checks is not more than 6
•  » » 4 years ago, # ^ |   0 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".
•  » » 4 years ago, # ^ |   0 Just follow the problem description. It's clear enough and you don't need to guess anything.
•  » » » 4 years ago, # ^ | ← Rev. 2 →   0 :/ ummm I think not, considering that the point of the contest is to give problem statements that you have to guess at
 » 4 years ago, # |   +3 How to solve H?
•  » » 4 years ago, # ^ |   +6 It's quite easy. To get an AC, you don't need to print anything!
 » 4 years ago, # |   +29 Lol??
•  » » 4 years ago, # ^ |   +10 You are not alone. I've submitted it for at least 40 times, and at last I failed.
•  » » 4 years ago, # ^ |   0 SAME HERE ... :( ... # WASTE OF TIME
•  » » » 4 years ago, # ^ |   0
•  » » » » 4 years ago, # ^ |   0 Bro, I did this searching stuff but I thought that we have to print an Integer.
•  » » » » » 4 years ago, # ^ |   0 but actually i print "red" and try several times
 » 4 years ago, # |   +5 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.
•  » » 4 years ago, # ^ |   -16 In B, you must output the type of cat as soon as you figure out what type of cat it is.
•  » » » 4 years ago, # ^ |   +16 I know, but it doesn't answer the question why the code int main() { assert(false); } `gets WA and not RE.
•  » » » » 4 years ago, # ^ |   0 Hmm, that's interesting... does codeforces ignore asserts, maybe?
•  » » » » » 4 years ago, # ^ |   +8 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.
•  » » » » 4 years ago, # ^ |   +6 Maybe this is also a part of the April Fool... :P
 » 4 years ago, # |   +7
•  » » 4 years ago, # ^ |   +4
•  » » 4 years ago, # ^ | ← Rev. 2 →   +3
 » 4 years ago, # |   0 In B, I was getting WA checking only given words. Then added "normal" and "grumpy" in the list. Guess what? LOL :p
 » 4 years ago, # |   0 For problem B, I just tried random and it works magic http://codeforces.com/contest/952/submission/36819128.
•  » » 4 years ago, # ^ |   +15 You can't fool me it's not random.
 » 4 years ago, # |   +18 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. ╮(╯-╰)╭
 » 4 years ago, # |   +11 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
 » 4 years ago, # |   0 How to solve F?
•  » » 4 years ago, # ^ |   +17 The editorials are up at http://codeforces.com/blog/entry/58681
 » 4 years ago, # |   +22 I shed tears after I finally knew the truth of D
 » 4 years ago, # |   0 When you got a bug in E and thought that you got the statement wrong...
»
4 years ago, # |
Rev. 2   -10

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

---

or

===

# |0|

or

100,9,25 square of number or

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

 » 4 years ago, # |   -10 Is it rated??
 » 4 years ago, # |   0 Hi Codeforces community... I was wondering why this contest is not listed in my Contest history ? Regards!
•  » » 4 years ago, # ^ |   0 since it is not rated.
 » 4 years ago, # | ← Rev. 3 →   0 Awesome!