csacademy's blog

Round #15 + Platform changes
By csacademy, 7 years ago, In English

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #15 will take place on Wednesday, 30/Nov/2016 16:00 (UTC). If you want to take part in this round you need to register before the contest begins. This contest will be a Div1 + Div2, with 7 tasks of varied difficulty that need to be solved in 2 hours and 30 minutes.

We are honoured to have josdas and bluemmb as problem setters.

Also many thanks to Yury_Bandarchuk for translating the problem statements in Russian.

Contest format:

  • You will have to solve 7 tasks in 2 hours and 30 minutes.
  • There will be full feedback throughout the entire contest.
  • Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
  • Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
  • Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

  • Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
  • Solutions that don't compile or don't pass the example test cases are ignored.
  • Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

Platform changes since Round #14

New forum

In the right side of the navbar, next to the blog section, you can find a link to our forum:

... and it looks like this:

The forum is build as a single page app, so you don't need to refresh the page to see new changes (votes and new posts update in real time).

Geometry tool

You can find it in the Apps section, below the Graph Editor:

More languages added

During the contest we don't guarantee the time limits will be calibrated for languages other than C++ and Java.

We still recommend using an updated version of Google Chrome. If you find any bugs please email us at [email protected]

Don't forget to like us on Facebook, VK and follow us on Twitter.

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

Wrong Date mentioned.

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

Perl :D

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

    Do you have any special compilation commands that you'll want?

    We have 0 to no experience with perl :)

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7 years ago, # |
← Rev. 2   Vote: I like it +22 Vote: I do not like it

The geometry tool is very useful, thanks.

but I think it still need some improvements.

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    7 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    Yeah, it's still kinda buggy, but we decided to launch it anyway :P.

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7 years ago, # |
  Vote: I like it +37 Vote: I do not like it

In conclusion, we should expect a lot of geometry problems this round, I suppose.

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7 years ago, # |
  Vote: I like it +87 Vote: I do not like it

Something is very wrong, site is down? Can't log in or submit problems :(

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7 years ago, # |
  Vote: I like it +22 Vote: I do not like it

I cant log in either, and the site is very slow, pls fix it.

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7 years ago, # |
← Rev. 2   Vote: I like it +20 Vote: I do not like it

Not able to login. Says "Invalid Token"

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

Why I cannot login?

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

Seems like introducing new features in the platform, didn't go well with the old ones!

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

Have tried even with Google accaunt, didn't work..

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

I cannot login too. I am using firefox.

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

the bug not fixed yet :(

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

can't login

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

Can we get any feedback about this?

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

It's been fixed now.

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

    I was able to make a submission and now I am logged out and same errors again!

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

    Submitting does not work for me.

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7 years ago, # |
← Rev. 3   Vote: I like it 0 Vote: I do not like it

Site is again down :(

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7 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Nothing happens when I click sign in... THis is after everyone is saying it is fixed?

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

Seems like it's OK now.

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

Can't submit! The button doesn't respond on clicking.

UPD: Oh, seems like it's been pushing my submissions in the queue without telling me...

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

We are sorry for the inconvenience, everything should be ok now. We are not sure if the contest will be rated or not, but it will be prolonged by at least 15 minutes.

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

Can't submit :/

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

    Try refreshing the page, it should work now.

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

Still not working?

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

    It's working now. If you have any problems refresh the page, please.

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

      about, csacademy, are all the tests applied to a submission, or it's like codeforces with pretests and final testing?

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

        We don't have pretests, so if your solution passes then it's accepted.

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

      I still cant submit (I refreshed the page, and close the browser), the site says that I'm not connected to the servers.

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

        Try refreshing the page, it should work now.

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

The site is down for me. Neither i'm able to compile or submit :(

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

    Try refreshing.

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

      Guys, come one.. I have tried to submit C problem for 20 mins..

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

        It says, too many submissions, but I when I check them, only 4 of them are made(which I made about 40 mins ago)

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7 years ago, # |
← Rev. 5   Vote: I like it +6 Vote: I do not like it

Workspace is nice for show-off, but not useful if it does not show meticulously in cases of high load if my code is getting submitted or not. Same code getting submitted multiple times due to site instability and not getting to know if it is getting submitted it or not until I check out my submissions 2-3 minutes later.

A simple file upload alternative mechanism should be in-place to submit code.

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

    +1, I don't know how I took +8 on third problem

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

    Did you accidentally press Ctrl+u? This hotkey submits the code.

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      7 years ago, # ^ |
        Vote: I like it +18 Vote: I do not like it

      Occam's razor: repeatedly clicking Submit is more likely than accidentally pressing a combination of keys located far from each other and from any other commonly used combination.

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

        Yes, this is exactly what happens. After pressing submit, half of time nothing shows up(like it is submitting or running or not) — so it is highly likely that one will press Submit again.

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

          Same, I was just lucky that my first submission got accepted :)

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7 years ago, # |
  Vote: I like it +60 Vote: I do not like it

Is it rated?

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7 years ago, # |
← Rev. 2   Vote: I like it +20 Vote: I do not like it

In problem "Substring Restrictions", I use two pointer to get k such that s[i] = s[i + k] or s[i] = s[i — k]. I just choose minimum and maximum k and join(i, i + k) / join(i, i — k). Surprising, it passes. Is test case weak?

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    7 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    At the same time my right solution got TL12, until I ran bruteforce in case of small len in query.

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

    If this is your solution, I can't understand why it passes the following testcase:

    6 5
1 1 4
1 2 3
1 3 5
1 3 4
1 4 6
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7 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Can someone discuss the approach for Base K Xor https://csacademy.com/contest/round-15/#task/base-k-xor/ ?

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

Where can I find editorials, if available?

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

I solved K based Xor using digit dp though it was not totally mainstream.

Nice problems :)

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