Rudro25's blog

Noobs Round #1 (Div. 4) Announcement
By Rudro25, 4 years ago, In English

Hello codeforces !

Muhammad_Saidul_Islam and I glad to invite you to our First round " Noobs Round #1 (div. 4) " .. The round will not be rated for any participants since it is unofficial.

You can virtually participate in the contest by clicking this link:

https://mirror.codeforces.com/contestInvitation/df49ade9db566204acd3653a7c3cacad088f6f1e

You can participate whenever you want, just click the link above and virtually participate. After enter in the problem-set we will give you 2.5 hours to solve the problem . After 2.5 hours you can not enter the problem-set again.

You will be given six tasks and 2.5 hours to solve them. The problems were created and prepared by Rudro25 and Muhammad_Saidul_Islam for users with a rating range from 0 to 1400 But anyone is welcome to participate in the round!

We would like to thank everyone who was involved in the round preparation:

  • wan-_-s ,AST_TheCoder for testing the problems and providing useful feedback.
  • MikeMirzayanov for Polygon and Codeforces platforms.
  • You for participating in this round. Thanks!

Even though the contest is unrated we believe it is a really good way of practice, especially for Div 4 users. We tried our best to keep the statements short and clear and we hope you will like our problems!

Good luck and Have Fun !

  • It's our First contest But we tried our best. So please consider our mistake . And if you find any unclear / wrong statement then please comment below .
  • If you use any illegal way . we will remove you from standing !

N.B. Editorial will be posted September 28 by Muhammad_Saidul_Islam or Rudro25. And We will open it for practice after 27 September , requesting you to wait .

UPD : Editorial Link

Congratulations to everyone !!

  1. conqueror_of_tourist
  2. Tlatoani
  3. smax
  4. YouKn0wWho
  5. rakshi20
  • Vote: I like it
  • +111
  • Vote: I do not like it

Comments Comments (21)
| Write comment?
»
4 years ago, # |
← Rev. 3   Vote: I like it +5 Vote: I do not like it

You will be given six tasks and two hours to solve them.

it's 2.5, isn't it?

→ Reply
»
4 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Statements are not clear at all sir. "if Alice or Bob go any box that called visited for both" and what does this line actually mean ?, looks like lack of English Translators.

→ Reply
»
4 years ago, # |
  Vote: I like it +5 Vote: I do not like it

Problem B is same with recent problem on codechef ARRGAME

→ Reply
  • »
    »
    4 years ago, # ^ |
      Vote: I like it +7 Vote: I do not like it

    It's a practice contest for beginners. What are you expecting!?

    → Reply
»
4 years ago, # |
  Vote: I like it +19 Vote: I do not like it

I feel like I saw this announcement before. :thonk:

→ Reply
»
4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Can we get a div 5?

→ Reply
»
4 years ago, # |
  Vote: I like it +2 Vote: I do not like it

How to solve F?

→ Reply
  • »
    »
    4 years ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    You solve the length part by dp. Make a 2D dp,where dp(i,j) means, maximum length subsequence upto i, such that the last letter is ('a'+j). Maximum length will then be the max of dp(n-1,j) for all j from 0 to 26. Let this be L.

    Then to reconstruct the answer, you can check from the end whether you should take this character or not. Find the first character for which dp(i,j) = L. Take this character and decrease L by 1. Then move to its index and continue from there.

    → Reply
»
4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Was problem D solved using greedy technique like some binary search stuffs. Or there was something else? If anyone can share the approach. Thanks!

→ Reply
  • »
    »
    4 years ago, # ^ |
    ← Rev. 3   Vote: I like it 0 Vote: I do not like it

    binary search

    first sort the array then check for every element in array from 0 to mid are there different numbers which are greater than or equal to 3* element if yes return true else false

    code
    → Reply
    • »
      »
      »
      4 years ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      I did greedy. The max answer possible in n so its always optimal to get lowest n killed. So just sorr the array and then take two pointer one for person getting killed and others for their competition mates of higher energy

      → Reply
»
4 years ago, # |
  Vote: I like it +26 Vote: I do not like it

Statements are written quite badly, more proofreading is required before making contests public...

→ Reply
»
4 years ago, # |
  Vote: I like it +46 Vote: I do not like it

First off, please don't take anything I say personally. I'm well aware of how difficult it is to prepare a contest, and I thank problem setters for taking the time to do this; I just want to provide feedback for next time. Kudos for successfully setting a round!

Pros:

  • I thought B was a very cute/nice problem (although a shame that apparently it's appeared on Codechef before, according to some other comment).

  • The problems were a reasonable difficulty for Div 4 (maybe a little bit hard?).

Cons:

As others have mentioned, problem statements were difficult to parse and had lots of mistakes. In particular:

  • Capitalization and Bolding: The way I skim problem statements is I look for visual cues like bold words to find the key components of the problem, and capitalization to see where sentences start and end. Sentences like "vovuh can select every three players and They fight between them." throw off the flow of reading because "They" is randomly capitalized in the middle. Lack of bold also means problem elements are hidden in the flavor text, increasing the likelihood of misunderstanding the problem.

  • Lack of Latex/Pretty Formatting: When stuff isn't put in latex formatting, it's not immediately obvious it's a function/variable (e.g. I didn't realize n('A') was a function denoting the number of occurrences of 'A' in the string for a long time). The unformatted pseudocode in problem E was off-putting. I think $$$N$$$ and $$$a_i$$$ were also not formatted in some instances.

→ Reply
»
4 years ago, # |
  Vote: I like it +3 Vote: I do not like it

The fact that i cannot view contest after competing is so annoying.. people cannot upsolve and if they want to, they need to create alt accounts to do so which is annoying..

Thanks for the contest btw.

→ Reply
»
4 years ago, # |
  Vote: I like it +8 Vote: I do not like it

very bad description in problem A. You should give a clear statement as well as a clear image.

→ Reply
»
4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve B??

→ Reply
  • »
    »
    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    They didn't correctly copy the conditions from Codechef. Check out the Codechef link in a comment above.

    → Reply