HolkinPV's blog

Codeforces Round #158 (Div. 2)
By HolkinPV, 12 years ago, translation, In English

Welcome, friends)

New year is coming and meanwhile we are glad to introduce you regular Codeforces round #158 for Div. 2 participants, may be the last in this year). Traditionally Div. 1 participants can take part out of the competition.

Today's problems were prepared by authors: Nikolay Kuznetsov (NALP), Fefer Ivan (Fefer_Ivan), Pavel Kholkin (HolkinPV) and Gerald Agapov (Gerald). Traditionally thanks to Michael Mirzayanov (MikeMirzayanov) for perfect Codeforces and Polygon systems and Mary Belova (Delinur) for translating the problems.

Score distribution will be standard.

We wish everyone successful hacks, high rating and happy new year!

UPD: the contest is over, we hope you enjoy it)

Сongratulations to winners:

1) ballmaids01
2) betalife37
3) showtime
4) vlyubin
5) bardek

UPD2: the tutorial is published, you can find it here)

  • Vote: I like it
  • +163
  • Vote: I do not like it

Comments Comments (68)
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12 years ago, # |
  Vote: I like it +15 Vote: I do not like it

http://xkcd.com/859/

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12 years ago, # |
← Rev. 2   Vote: I like it +56 Vote: I do not like it

It will be nice if somebody will make Div 1 contest before the new year.

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

158 Div 2 = 79 = 47+4*7+4

gl && hf :))

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

I want to know how scores distribute in this contest.

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

It will be nice if my rating is beyond 1700 first before the new year

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

Polygon systems?

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

Thanks. :) It's Nice to Have a Contest Before New Year !

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

It will be my first contest; I'm so excited! Thank you to all who create this!

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

Will input/output files be required or should we read from and write to the standard input?

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

    IF SOMETHING REQUIRED , IT WILL BE CLEARLY SAID . . . BEFORE CONTEST.

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

why +5 min?

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

wish you good luck everybody...

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

"We wish everyone successful hacks" successful hacks means unsuccessful solving attempt. Why did you wish that?

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

    We told about it so many times :)

    unsuccessful solving attempt and then we can fix it and save points

    successful solving attempt and failed system test => lose so many points

    That's all

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

    In olympics games, Why do you cheer for your country ??

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

      http://en.wikipedia.org/wiki/Patriotism

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

        even if you don't know sportsmen personally. What's the point of winning some competition for any country. It causes pride more often than "patriotism" — that is naturally kind of responsibility for all good people and, esp. children living in your country. (IMHO)

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

          Of course, you're right. But what you talk about has got some patriotism in it, I think. :)

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

        Only point I was trying to make through this was this : In a competition ,one will surely win and other one will lose. So winning of one team will lead to loss of other one , but you will wish your team best of luck. You do not feel bad for losing one.( you might but you do the first part sure(wishing your own team)). So similarily in this case a successful hack to one person will surely cause other submission to fail. So I do not think wishing a succesful hack is bad.

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

i keep getting runtime error on testcase 1 div 2 problem B, code runs fine locally, what is wrong?

submission 2841685

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

    We can't view your submission untill contest's end

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

      ok, doesn't matter, i found out what was wrong..

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

Very nice thinking problems . A was looking so difficult, but after the logic it is damn easy. I liked the last contest of the year :)

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

Oh. I'm too old for this, Shire.

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12 years ago, # |
← Rev. 3   Vote: I like it +11 Vote: I do not like it

Hi, I made an unsuccessful hack, then I tried to go back to look at the defender's code again, reloaded the page, etc. and somehow got my bad hack re-sent! (and no, I did not click the button twice).

For the current round, it doesn't matter to me because I'm participating out of competition, but it would be nice if the system wouldn't allow me to send the same hack twice (to the same solution of the same participant), in the same way as the system does not allow me to submit twice the same solution code.

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12 years ago, # |
← Rev. 2   Vote: I like it -17 Vote: I do not like it

deleted

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12 years ago, # |
  Vote: I like it -27 Vote: I do not like it

Problem C — there isn't any word in the description about "initial condition of ai" must be non-negative.

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    12 years ago, # ^ |
      Vote: I like it +55 Vote: I do not like it

    How exactly you can have -1 ball in the box?

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

      I know, it's really illogical. But I think there should be an explicit word such as :

      Print n non-negative integers, where the i-th one represents the number of balls in the box number i before Vasya starts acting.

      Unless the writer wanted this to be tricky situation.

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        12 years ago, # ^ |
        ← Rev. 5   Vote: I like it +3 Vote: I do not like it

        This happens a lot of times to me also. I read the problem statement and if I read it wrong , then I later start blaming English or some similar issue. When I again read the problem statement , It seems crystal clear.

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

        Maybe this: (it is guaranteed that this box originally had at least one ball)

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

          That only refers to box i.

          Although it's possible that the problem is to be taken "by common sense" that no box can have a negative number of balls.

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

    Thats because the balls made of antimatter are not so common.

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

    problem C isn't pretty clear for me as well, there isn't any description about initial value of ai, according to this statement "(it is guaranteed that this box originally had at least one ball)" during the contest I thought this statement occurred to the other boxes and this really affected to my solution which failed in the system test

    well this is just my opinion and I hope next round will be better

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

Wow Amazing system testing speed.

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

The best presents — good problems and fast system testing. Thanks a lot :) Happy New Year!

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12 years ago, # |
  Vote: I like it -17 Vote: I do not like it

i didnt like this contest :(

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

Please update with link to editorial/tutorial/contest analysis (English preferred) when it's ready. Thanks!

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

Thanks for rapid testing! and Happy New Year!:)

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

At the problem A. AddingDigits, It's said that "In a single line print the integer". The output correct output contains Numbers instead of integers ?

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    12 years ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    Do not think do much in programming languages, you even forgot the definition of integer :P

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

      I thought that was the trick in the problem :D

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

It was an amazing contest :-) Good problems and Fast System test. waiting for the rating now !

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12 years ago, # |
  Vote: I like it +7 Vote: I do not like it

I am promoted to DIV1 for the first time (1721 rating). The best new year present:)

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

Rating Updated..

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12 years ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it

Can I ask probably stupid question but is it possible that there will be one more contest until new year?

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

    This is good idea,please admins will be also 1 contest before new year please!!!!!!

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

    If this happens I will be happy

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

Problem C Test: #24 ... could u give me...

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

This was probably the best codeforces round ever ! :) The problem set was very nice and balanced ! :)

Thanks for the nice contest and have a happy New Year :) !

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

thank you the contest was great. happy New Year to every one and hope somebody make contest before the new year.

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

Can anyone spare a small hint for Problem -- E?

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

Nice contest!! Waiting for another one!! :)

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

i solve problem E in O(9!logn^2) , about 200 lines codes, but I see other's code is so short...is someone know how to solve is simply?

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

So in problems C test15,

wrong answer 21st numbers differ — expected: '0', found: '13'

What about this words ? "...(it is guaranteed that this box originally had at least one ball)..."

somebody, please, explain it to me.

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

    11th test*.

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

      ohh, sorry. I'm inconsiderate(((

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        12 years ago, # ^ |
        ← Rev. 2   Vote: I like it +5 Vote: I do not like it

        the statement "_it is guaranteed that this box originally had at least one ball_" have talk about the selected ball! It does not mean that every box originally had at least one ball :)

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

          Yeah, thx. I'm so unobservant.))) I accepted it aleady.

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

Editorial is published here

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