### goryinyich's blog

By goryinyich, 10 years ago, translation,
Hi there!

Me - Sergey Vedernikov - is the author of today's CF beta round.

During the round you'll assist far away kingdom citizens in solving everyday problems, and sometimes - just to fight for your survival.
This round is "red" =), therefore the problems should not appear too difficult, and you should get pleasure from solving them.
To those who know Russian language I recommend to read problem statements in Russian. Not because of the quality of translation - English just poorly communicates Russian folklore language style.

Finally I want to thank Artem Rakhov for invaluable help during the round preparation, Maria Belova for the qualitative translation of the problems, Mikhail Mirzayanov for excellent CF system and all participants for not leaving this event without your attention.

More AC verdicts and high rating to all of you! gl & hf

UPD: Unfortunately, problem B (div. 1) / D (div. 2) appeared to be more difficult, and author's solution appeared wrong. The round will be unrated. I apologise for this to all participants.

• +42

 10 years ago, # |   +6 What do you mean by "This round is red" ? Nice rating by the way ;)
•  10 years ago, # ^ |   +14 This was joke for you to remember "first violet round" =)
•  10 years ago, # ^ |   +1 do you increase your rating every year and now your rating is 2011? :p
•  10 years ago, # ^ | ← Rev. 2 →   +15 "This round is red" (literally) means that this round is made by red CF user. There is a difference between 'red' and 'orange' rounds. (by the way, 'violet' round was not so 'violet' because of anonymous help :) ).
•  10 years ago, # ^ |   +12 1. Fall to violet2. Create a meme3. Become orange back4. ???????5. PROFIT
•  10 years ago, # ^ |   +11 > Fall to violetFail to violet ;)
•  10 years ago, # ^ |   +19 Red round
•  10 years ago, # ^ |   -10 Red standing.yellow, black , blue fallen down.Red staring at yellow :-oNice :-D
•  10 years ago, # ^ | ← Rev. 4 →   +5 Попробовал в Google+ написать сообщение в блог.Так вот, при добавлении ссылки на этот пост умный Гугл выбирает заодно и картинку выше.(в предыдущей правке скрин, но более подходящее ему место в этой теме: http://codeforces.ru/blog/entry/2278)
 10 years ago, # |   0 Problems sound easy... :D
•  10 years ago, # ^ |   0 Easy problems! gl & hf
•  10 years ago, # ^ |   0 very easy
•  10 years ago, # ^ |   +1 Very easy . Say Again
•  10 years ago, # ^ |   0 Toooo much easy.........
•  10 years ago, # ^ |   0 Oh it wasn't easy for me. :( (But author said it would be easy :P)
 10 years ago, # |   -11 GOOD LUCK!!!!!!!!!
 10 years ago, # |   0 How is red round correlated to easy problem set? Isn't it the other way? Am I missing something here?
•  10 years ago, # ^ | ← Rev. 2 →   -8 >Am I missing something here?Yes:Sarcasm
•  10 years ago, # ^ |   -32 меня одного бесит его рожа?
•  10 years ago, # ^ |   0 Не превращайте хотя бы эту ветку в га**о.
•  10 years ago, # ^ |   +1 Вы этому способствуете ;).
•  10 years ago, # ^ | ← Rev. 5 →   +4 This is English thread.
•  10 years ago, # ^ |   +22 I, for one, would be grateful if you created your own trash thread and refrained from posting images elsewhere. These images consume too much space for too little sense. Try and be polite. Thank you.
•  10 years ago, # ^ | ← Rev. 7 →   +5 一畫勝千言By the way, ACRush, many thanks for that translation at ICPC World Finals!
•  10 years ago, # ^ |   0 Not an English thread anymore?haha lose
•  10 years ago, # ^ |   +1 This is Chinese proverb. Am I wrong writing it in Chinese?
•  10 years ago, # ^ | ← Rev. 2 →   -9 Introduction to Algorithm no words!....
•  10 years ago, # ^ |   0
•  10 years ago, # ^ |   0 ок, Шеф
 10 years ago, # | ← Rev. 2 →   -12 good luck everyone :D
 10 years ago, # |   -12 thanks a lot. high ratings to all :)
 10 years ago, # |   0 I am new to codeforces...I have'nt seen the contest interface..Can anyone guide me ..Also I am using Java..So some technical help would also be great...
•  10 years ago, # ^ |   +20 Use Arrays.sort!
•  10 years ago, # ^ | ← Rev. 3 →   +3 So you can swap some random elements and everything will be OK.
•  10 years ago, # ^ | ← Rev. 2 →   -14 Once I've tried to make a 'Pifia' in one AI challenge. The sense was to predict Java environment random generation due to known calls to random generator. I've failed because of a bug in challenge API, but sometimes random prediction is possible :)
•  10 years ago, # ^ |   -10 :)
 10 years ago, # |   +4 Good luck everybody.Thanks to the problem setters for their contribution
 10 years ago, # |   0 good luck!)
 10 years ago, # |   0 Any idea for problem C div II?
•  10 years ago, # ^ |   +1 My solution was to try every combination, ignoring the rotation constraint, and save them in a array. Then I took every combination in the array and make all the rotations from it and erase these rotations from the list, the answer was the number of solutions left in the array.
 10 years ago, # | ← Rev. 2 →   +1 Do anybody know pretest 6 of problem B (Div 1)?
•  10 years ago, # ^ |   +1 maybe is n = 611/3
 10 years ago, # |   +18 Now I know what a RED round means.
 10 years ago, # | ← Rev. 3 →   0 This round probably has the most number of unsuccessful attempts (in DIV 1). Looking forward to the tutorial :P.
 10 years ago, # |   0 Nice problemset - I've solved only E and placed 22nd (hope it won;'t change after system tests).
 10 years ago, # |   +7 I think that problems were difficult because of the some (hard to understand) sentences...
•  10 years ago, # ^ |   0 such as...?
 10 years ago, # |   0 in A was there any pretest in which integer part ended with 9? i forgot to check out solutions in hacking phase.i doubt there was not such case , so many solutions will fail.
 10 years ago, # |   0 Div2 C: Can we use a brute force approach?
•  10 years ago, # ^ |   +1 Yes you can, try out all the permutations (which is at most 6!).
•  10 years ago, # ^ |   +1 yes, brute force works: there are 720 permutations of 6 colors, and 24 equivalent positions for a cube.It would therefore need 720*24 checks.  It's low.
•  10 years ago, # ^ |   +1 can you explain the 24 positions.How do i figure it out.Thanks for the help.
•  10 years ago, # ^ |   +5 bottom - 1 from 6.front - 1 from 4 which have the same bottom.
•  10 years ago, # ^ |   +1 1 identical transformation9 rotations around 3 lines connecting the opposite faces (by 90 degrees)6 rotations around 6 lines connecting the opposite edges (by 180 degrees)8 rotations around 4 lines connecting the opposite vertices (by 120 degrees)
•  10 years ago, # ^ | ← Rev. 3 →   +5 It's a group isomorphic to S4. A rotation of the cube corresponds to a permutation of the four diagonals.
•  10 years ago, # ^ |   0 Thanks guys for the help.it sounds a little too difficult for me.I did 720 permutation but lost track how to do the rotations <24>.can anyone give me some links where I can get these 24 positions or how can i do it?Thanks for your help again.
•  10 years ago, # ^ | ← Rev. 2 →   0 Actually you can use the stupid approach: Just brute force over the 4x4x4 ways to spin the dice in the X, Y, and Z axis.
•  10 years ago, # ^ | ← Rev. 5 →   0 24 step :0,0,0,1,0,0,0,1,0,0,0,1,2,0,0,0,1,0,0,0,1,0,0,0---------------------------------------------------0: +---+ | 5 | +---+---+---+---+ | 3 | 0 | 1 | 2 | -----> +---+---+---+---+ | 4 | +---+ +---+ | 1 | +---+---+---+---+ | 5 | 0 | 4 | 2 | +---+---+---+---+ | 3 | +---+1: +---+ | 5 | +---+---+---+---+ | 3 | 0 | 1 | 2 | -----> +---+---+---+---+ | 4 | +---+ +---+ | 5 | +---+---+---+---+ | 0 | 1 | 2 | 3 | +---+---+---+---+ | 4 | +---+2: +---+ | 5 | +---+---+---+---+ | 3 | 0 | 1 | 2 | -----> +---+---+---+---+ | 4 | +---+ +---+ | 1 | +---+---+---+---+ | 4 | 2 | 5 | 0 | +---+---+---+---+ | 3 | +---+http://codeforces.com/blog/entry/2325
 10 years ago, # |   +18 Nice problems - however, I don't think it was balanced.Number of submissions that passed the pretest are {A:218, B:20, C:29, D:21 and E:27}.  - Big gap between A and others. - (B C D E) very close to each other.For problem B, i think the example cases were too trivial.
•  10 years ago, # ^ | ← Rev. 2 →   +4
• 10 years ago, # ^ |
Rev. 2   +3

### Déjà vu

- and also, the lengthy statements made the problems hard to understand.
•  10 years ago, # ^ |   0 I think at the end of the testing would be even less :)
 10 years ago, # |   +9 Annoying problem statements. My B (div2) is going to fail because I failed to grasp the peculiarity of the statement till I locked my solution and checked another coder's solution.Problems overall were nice, though tough.
 10 years ago, # |   +10 I suggest that this contest is unrated.
•  10 years ago, # ^ |   +11 Why?
•  10 years ago, # ^ | ← Rev. 3 →   +14 We suppose that the jury's solution for B (Div. 1) is incorrect, and this problem doesn't have a correct solution for n ~ 1017.
•  10 years ago, # ^ |   0 any details?
•  10 years ago, # ^ | ← Rev. 2 →   0 See my solution 560061 for small n. It gives better answers than the jury's one.
•  10 years ago, # ^ |   0 What do you mean by "doesn't have a correct solution for n ~ 1017" ?
•  10 years ago, # ^ |   0 The answer can be quite long ;)
•  10 years ago, # ^ | ← Rev. 2 →   0 Probably the answer will contain too many digits. I'm not sure, I haven't investigated the situation carefully. Some participants wrote something about it in russian comments. In any case, the problem is much more difficult than it was supposed to be.
•  10 years ago, # ^ |   +1 So, the question to the author. Will you reduce the constraints so that the solution is possible to print, and explain it in editorial?
•  10 years ago, # ^ |   +4 even Petr didn't try this problem at all (didn't submit)
•  10 years ago, # ^ |   +20 Clever guy Petr, huh? :)
•  10 years ago, # ^ |   +1 How did Petr know it ....Petr is the god in my heart 4ever!
•  10 years ago, # ^ |   +9 I believe it's simpler than what you guys think, he just couldn't find a correct solution :)
•  10 years ago, # ^ |   +14 Petr is so cool that he always knows which problems have wrong jury solution
 10 years ago, # |   +6 Div-2 BI was able to hack a solution just because the participant didn't put '.' after Unrecoverable configuration
•  10 years ago, # ^ |   +5 all praise to your keen eyes.
•  10 years ago, # ^ |   +7 Why wasn't there a pretest for this?
•  10 years ago, # ^ |   +5 Because it would create an unrecoverable configuration =)
•  10 years ago, # ^ |   0 Uhm... When I wrote my B (div2) I made a copy-paste error: my solution never printed "Unrecoverable.." but printed always "Excellent pages" instead. I sent it, and failed on pretests! Then I corrected it and got it accepted.How is it possible?
•  10 years ago, # ^ |   0 actually the participant had checked for "Unrecoverable Configuration." at 2 places. At one he forgot to put '.' :)
•  10 years ago, # ^ |   0 Ok I understand now :)
 10 years ago, # |   +10 That was a hard and unballanced round. Also, I missed the usual explanation of the sample cases in some problems in Div 1, mainly B and E...
 10 years ago, # |   0 oh, no..........
 10 years ago, # |   +13 I really enjoyed the contest. Perhaps a good warm-up (if not overheat) before tomorrow's TCO.I will be really really really looking forward to E's editorial.
•  10 years ago, # ^ |   0 enjoyed the contest, yes, but it's unrated :(anyway good luck for tomorrow's TCO then :D
•  10 years ago, # ^ |   0 Can we expect CodeForces rounds authored by you soon?Your TopCoder contests were cool and Hard problems were as tough as today's problemset if not more ^_^
•  10 years ago, # ^ |   +30 Thank you! I'm very happy to hear that.I've asked to but haven't got any reply until now. Maybe they already have too many authors - or maybe they simply missed my email. In either case you have the answer.
•  10 years ago, # ^ |   +29 I don't know what happened with your email, but will be really great to see your round on Codeforces. I'll ask RAD to ping you about it. Thank you.
•  10 years ago, # ^ |   +29 Thank you! I've received the follow-up email and let's see what will happen next :)For those who didn't know how to author problems for codeforces, here's a link: http://codeforces.com/help#q5
•  10 years ago, # ^ |   +12 Agree with caustique, dolphinigle's contests are awesome.In fact, he is our favorite in Indonesia :D
 10 years ago, # |   +21 After 13 days waiting for this contest. to be unrated! :(
 10 years ago, # |   +18 Hmm.....unrated..It makes me sad ;(By the way , I couldn't get pleasure from solving these because it seemed that problems are very difficult except for A!I think that recent contests are becoming difficult than the contests of the past clearly.
 10 years ago, # |   +5 My contest performance was very bad.Cannot solve problem C. But who cares the contest is unrated so I m feeling lucky...................
 10 years ago, # |   0 Shocked............... :-( :-("Unrated" !!!!!!!!!it's not sounds good........ :-(
 10 years ago, # |   +8 Why interval between contests have increased? We would love to have 2 contests in a week,at least 1.
•  10 years ago, # ^ | ← Rev. 2 →   +13  Having not enough nice problems for the contest.
•  10 years ago, # ^ |   +8 Preparing to Petrozavodsk Camp (?!)
•  10 years ago, # ^ |   -11 I'm sorry,but..what's that?!
•  10 years ago, # ^ |   0 Petrozavodsk Training Camp (http://karelia.snarknews.info/, Russian only) is NEERC teams training camp with 9 original 5-hour contests.
•  10 years ago, # ^ |   0 2 contests in a week would be nice.shorter problem description with no translation error would be nicer.good & balanced problem set will be even better.I look forward to it.
•  10 years ago, # ^ |   0 well, you can complain about the translation errors to me personally (as I translate the problems), I'm open to criticism (within reasons, of course))
 10 years ago, # |   +1 In B (Div1)/D (Div2), how to proof that a given strategy is an optimal one ?
 10 years ago, # |   +6 I don't know if I'm missing something, but if the author solution for the "B div1/D div2" was wrong. How did 21 coder manage to get it accepted ?!!
•  10 years ago, # ^ |   +6 They have the same wrong solution...
•  10 years ago, # ^ |   +3 So, they had the same wrong thoughts, and made the same mistakes as the problem setter ?!
•  10 years ago, # ^ |   +5 Exactly.
 10 years ago, # |   +7 This contest supposed to be rearranged as like as SRM504.5
 10 years ago, # | ← Rev. 3 →   -13 Can this contest be rerated with the ignorance of AC solutions in B (Div1)/D (Div2)?I think it's better than unrated....
•  10 years ago, # ^ |   +4 What with people who spent time on problem B/D?
•  10 years ago, # ^ |   +6 I spent time on B, but I wish the contest to be rated :D
•  10 years ago, # ^ |   0 pdwd is right
 10 years ago, # |   0 I think it's better to rematch in few days.
•  10 years ago, # ^ |   +5 Waiting for Codeforces Beta Round #78.5 :)
 10 years ago, # |   0 Any editorials coming soon??? or not? :(
•  10 years ago, # ^ |   +1
 10 years ago, # |   0 This was my first contest and goes of unrated....disappoiting:(
 10 years ago, # |   -16 Now I know the meaning of "red"for me "red" means hard but unrated with pretty large stories.
 10 years ago, # |   +5 Round #79 and #80 is coming soon
 10 years ago, # |   0 Many contests are coming soon. It feels nice :))
 10 years ago, # |   0 Why isn't 98B in the PROBLEMSET rejudged? The problem has already been modified.
•  10 years ago, # ^ |   0 I don't have neccessary rights. It will be rejudged soon.
 » 5 years ago, # |   0 There is a tutorial written for this contest — http://codeforces.com/blog/entry/2323 . Thanks to #AndreySiunov (in the comments) for that. But there is no link for it. on the contest Dashboard. Please add it. I had a hard time finding it.