Ripatti's blog

Codeforces Beta Round #65 (Div. 2)
By Ripatti, 11 years ago, translation, In English
Hello everyone!

I am an author of today problemset. It is my second round on Codeforces. I hope you will like this round like my first one:)

Good luck!

UPD
Winner is unicef.
Editorial.
 
 
 
 
  • Vote: I like it
  • +102
  • Vote: I do not like it

11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Which was your first one?
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
good luck to all :D
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11 years ago, # |
  Vote: I like it +4 Vote: I do not like it
I have a doubt regarding the contest timings.In the mail I received , its mentioned that the timing is Tuesday, March, 29, 2011 16:00 (UTC)  
which turns out to be 8:30 pm in India.
But in the last codeforces match codeforces beta-64 the timing mentioned in the mail was  Saturday, March, 26, 2011 16:00 (UTC)
which turns out to be 9:30 pm in India.
How is it possible that the same time on different days is differed by 1 hour?
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  • 11 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it
    Daylight saving
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    • 11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      This time is better for Bangladeshi contestants I think...
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  • 11 years ago, # ^ |
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    Same problem here . When i reached home at 9.30 pm, saw that i am late by 1 hour.
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  • 11 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    In this saturday time in Russia was increased for 1 hour. That's for the last time.
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11 years ago, # |
  Vote: I like it +6 Vote: I do not like it
Problems D and E were not what I expected from codeforces.
Reading input and Writing output in Problem E was the hardest point in this problem and this is not how the standard codeforces tasks look like.
I hope problem setters understand that it's not cool to make the output readable for humans by making it long and hard-to-print.
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  • 11 years ago, # ^ |
      Vote: I like it +24 Vote: I do not like it
    I guess that output format that contains not only "YES" or "NO" is needed to check that answers found by participants are correct as well as to check that situation when contestant found the solution while the author program didn't , doesn't happen. I didn't like it much either, but it is understandable.

    Besides that I don't think that reading input and writing output is the most difficult part of problem E but we shall not discuss that before the end of the contest:)
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  • 11 years ago, # ^ |
    ← Rev. 2   Vote: I like it -17 Vote: I do not like it
    Think output format for D should be tested on pretests completely and not give penalty for it, because I received +3 on it with forgotten dot at the end and double space :( .
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11 years ago, # |
  Vote: I like it +9 Vote: I do not like it
problem C was nice, understandable and approachable both :)
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Sorry, I am afraid of  saying that this contest is a little boring,the last two problem needs too much code ,but few about algorithm!.

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11 years ago, # |
  Vote: I like it +7 Vote: I do not like it
I agree with what some people have said, problems D and E were not quite the best.

A: was very straightforward, but that's fine, specially in div 2 only.
B: was easy but needed a little thought.
C: was great, the statement was clear, needed thinking and solutions were nice.
D: was long and boring overall, just tons of code without much thinking was enough.
E: I didn't have time to tackle it in the contest, but seemed approachable, but I really didn't like the fact that looking for periodic tables was part of it. That may be more real life like, but in programming contests the speed and skills to find a periodic table that can be put on code fast seemed overly boring to me.

NOTE: I just mentioned this as my opinion, I appreciate all the effort the codeforces team puts into the contests, but those last two problems seemed to me that having div 2 only so often is making the writers to run out of nice problems quickly.
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  • 11 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it
    The problem setter could have easily replaced the atomic symbol with just atomic number or provided atomic symbol along with atomic number. Then it would have been a great problem... In programming contest even in the online contest searching google for data can be just interesting but not conventional. Here we are for our coding and algorithmic contest , not for searching contest... by the way problem E was very good if we ignore this fact..
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Hi, firstly, nice contest!

But… :) I think there was too "coding hard" problems D and E. In problem E, i would appreciate for example list of all possible atoms, cause i won't have to rewrite them by hand…
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  • 11 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it
    Yes, they were hard to code, but they were interesting) 

    I also think, that is was good contest!
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11 years ago, # |
  Vote: I like it +1 Vote: I do not like it
my C failed just because of array size,RTE. felling terribly bad.
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11 years ago, # |
  Vote: I like it +2 Vote: I do not like it
Why is ratings change taking so long?

Plus, it is a bit weird that so many people end up having the same standing in the contest (same score). Thus you could have a standing of say a 90, only to find out that there are actually 300 people above you. I think we need a more granular scoring system.
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11 years ago, # |
  Vote: I like it +3 Vote: I do not like it
system test taking longer than usual.. I guess ratings change will take longer too..
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11 years ago, # |
← Rev. 3   Vote: I like it 0 Vote: I do not like it
system test taking longer than usual.. I guess ratings change will take longer too..
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
I have a question about Problem E. 

Input:
5 2
H H H H H
He He

Which is expected answer ?
---
NO
---
or
---
YES
H+H->He
H+H->He
---

In fact, I passed both pattern solutions in practice.

... Or , is this invalid input?

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  • 11 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    That's definitely invalid, because 'The sum of numbers of initial atoms is equal to the sum of numbers of the atoms that need to be synthesized'
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  • 11 years ago, # ^ |
    ← Rev. 5   Vote: I like it 0 Vote: I do not like it
    Thanks ant.ermilov_HI(Not blue)I!
    I have noticed the statement now. 

    "The sum of numbers of initial atoms is equal to the sum of numbers of the atoms that need to be synthesized." 

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    • 11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Plz, fix your post, I'm violet now :)
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      • 11 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        ok. I fixed the post :)

        Congratulations on a purple coder!

        By the way , The new rating system seems to be too severe.
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        • 11 years ago, # ^ |
            Vote: I like it +1 Vote: I do not like it
          Agree. I expected around +100 rating change.
          But this fix advantage for div2 coders and it will be harder to get into div1 through div2 only contest.
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        • 11 years ago, # ^ |
          ← Rev. 2   Vote: I like it 0 Vote: I do not like it
          Sorry. Doublepost.
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
can anyone tell how to do question 3?
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11 years ago, # |
← Rev. 2   Vote: I like it -11 Vote: I do not like it
Problem E was too easy to code? You could have replaced the atom names with the number of their atomic number in words. In other words, you would say ninety nine instead of 99. This can be variable (ex you can say ninetynine or ninety-nine or in any human understandable format, occasionally also replacing with roman numerals). Also you could have removed the restriction of 100 and made it all the way to thousand (or one thousand). This would have made the contest more interesting.
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  • 11 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it
    I don't agree. For me the most difficult part of your problem is English knowledge.  (native speakers have too much advantage).
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    • 11 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      Dear rng_58,
         Firstly I am a great fan of you. Bows!
       Secondly my statement was just sarcastic.
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11 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Соревнований уже давно нет. Кто-нибудь знает почему?
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11 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I'm confused that some test case(just like #85) in problem E take over 20s to get result in my own computer, but it still got AC(with 600 ms) when I submit. Why ? I have tested some codes of others' and have the same problem. I don't think my computer runs 50 times slower than the server's. 
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  • 11 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it
    May be you compile your code in the debug mode or in the release mode without -O2 flag.
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    • 11 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Amazing ~ Thank you so much ~ Compiler is fantastic~ A 5*10^8 times loop can run out in a second..
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