MikeMirzayanov's blog

Testing Round 19 [unrated registration testing]
By MikeMirzayanov, history, 2 weeks ago, In English

Hello!

We are starting to test the long-awaited feature of non-rated registration for rounds. Here’s the plan: we will first test this feature in Testing Round 19 (Div. 3). Then, we will apply this innovation for ICPC-like rounds (Div. 4 Rounds, Div. 3 Rounds, Educational Rounds). After we have tested the feature in ICPC-like rounds, we will start using it in other types of rounds as well.

Here’s how the feature works:

  • When you register for a round (if it is rated for you), you can choose non-rated registration if you do not expect to perform at your best (for example, if you might be interrupted during the round).
  • You can change your registration type (rated or non-rated) BEFORE THE ROUND STARTS. Once the round starts, you cannot change your registration type.
  • If you register for a round after it has started, you will automatically be registered as rated (if the round is rated for you). In other words, you will not be given the option to register as non-rated.
  • After the round, the rating will be updated only for those who participated in the round and had a rated (regular) registration.

During the round, you will not be able to see whether another participant is registered as rated or non-rated. You will be able to find out later by checking if their rating has changed.

We urge you not to abuse this feature in the future and to try to participate in rated mode. Use this option only if you have a valid reason.

Let's test the new feature together: participate in Testing Round 19! We advise you to randomly choose your registration type so that we have both rated and non-rated registrations.

After the round, we will temporarily recalculate ratings to ensure everything works correctly. After that, of course, the rating changes from Testing Round 19 will be removed.

Thank you for participating!

UPD: Thank you all for testing! Share your feedback in the comments. The ratings for this round will be rolled back within a few hours.

  • Vote: I like it
  • +993
  • Vote: I do not like it

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

hoping positive delta

does choosing rated in testing will change my rating. ?

→ Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    Mike said:"the rating changes from Testing Round 19 will be removed."

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

Is it ok that I can't register in unrated mode?

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

    In the upcoming div.3, I registered as a rated participant. If I become expert in tomorrow's div.2 will my participation in the div.3 be automatically changed to unrated, or will it still remain rated for me?

    → Reply
»
2 weeks ago, # |
  Vote: I like it +33 Vote: I do not like it

I cannot register?

"Rating should be between 0 and 1,599 in order to register for the contest"

→ Reply
»
2 weeks ago, # |
  Vote: I like it +6 Vote: I do not like it

Is it rated? xD

→ Reply
»
2 weeks ago, # |
  Vote: I like it +9 Vote: I do not like it

maybe a prior announcement would've resulted in more participation.

→ Reply
»
2 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

Will the rating change be calculated based only on rated partecipetion or will unrated users also count?

→ Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    only who choose it to be rated* . Otherwise what is there to test, it would be same as a normal div 3

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

      ohh my god... I didn't know about this... can someone please tell me, if contest will be rated for me or not :| . How do I check whether I registered rated or unrated !

      I wasn't aware of this. First time in my life, I have chance to reach close to CM, looks like I messed up due to change in registration process :| . :(

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

hooray! >.<

→ Reply
»
2 weeks ago, # |
← Rev. 2   Vote: I like it +15 Vote: I do not like it

Good initiative, this will definitely reduce alt participations

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

Wow, amazing!

→ Reply
»
2 weeks ago, # |
  Vote: I like it +7 Vote: I do not like it

Great. You won't be waiting till the end of a contest to practice virtually :)

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

are there original problems lol

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

WoW This is crazy!!!!!

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Is it possible to change back to unrated after going from unrated to rated?

→ Reply
»
2 weeks ago, # |
  Vote: I like it +28 Vote: I do not like it

Right now, if one registers for a round and does not make a single submission, their rating does not change. Will this rule change? If I register for a rated participation and forget about it later, will I lose rating?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

if I participate as a rated participant but didn't submit any code, will I get negative delta ?

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

Thats a great idea!!!

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

On registration page there is "Read the details in this post.", but post is inaccesible

→ Reply
»
2 weeks ago, # |
  Vote: I like it +47 Vote: I do not like it

wait

If you register for a round after it has started, you will automatically be registered as rated (if the round is rated for you). In other words, you will not be given the option to register as non-rated.

Shouldn't this be the opposite? Like if you start late there is all the more reason that you might have assessed that you will do well in this round by seeing the questions. It's also not too far fetched to say one might also solve questions in those 10 mins of late registration wait, making it essentially the same as rated registration from the start, so really it's just rated registration with an advantage of assessment and disadvantage of not being able to do AC in the first 10 mins.

→ Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +50 Vote: I do not like it

    I personally don't see any reason why both options can't be allowed during the round.

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

    What if someone spends first 1h of the round cracking D1D-D1E solution, and if they are suceeding, right before submitting it, change participation to rated.

    → Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

let's do some speedrun

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Just curious, who are the writers of this round?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

no way!

→ Reply
»
2 weeks ago, # |
  Vote: I like it +97 Vote: I do not like it

If this feature is applied to div1, due to the limited number of rooms in div1 (only about thirty to forty), some groups might collectively become unrated and write incorrect codes. If rated and unrated participants are placed in different rooms, it would contradict the rule: "During the round, you will not be able to see whether another participant is registered as rated or non-rated." So why should participants be prohibited from knowing whether others are rated?

→ Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +34 Vote: I do not like it

    Indeed. This would also break rating predicting tools like carrot, specially because people participating unrated are expected to perform worse on average. Unrated users could show as "out of competition" just like Div1 participants show on Div3 or EDU standings.

    → Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +27 Vote: I do not like it

    Rated trying to hack unrated and viceversa doesn't makes any sense. Totally agree with you.

    → Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it +32 Vote: I do not like it

    Also

    If you register for a round after it has started, you will automatically be registered as rated (if the round is rated for you). In other words, you will not be given the option to register as non-rated.

    I think the AtCoder version (i.e., you will automatically be registered as unrated if you are late, and rated participants will have rating changes regardless they submit or not) is more reasonable. As that's exactly AtCoder want to do with those dudes checking AGC F first and if solvable then submit and gain positive delta, otherwise skip the round.

    → Reply
    • »
      »
      »
      2 weeks ago, # ^ |
        Vote: I like it +16 Vote: I do not like it

      Right now the participants can register as rated, and leave the contest without making any submission after reading the problems. So I don't think it's any worse than the current situation.

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

        I would have thought that Mike will adopt the whole AtCoder solution, as I expected here.

        → Reply
»
2 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

Just atcoder thing, well nice initiative.

→ Reply
»
2 weeks ago, # |
  Vote: I like it +21 Vote: I do not like it

Giving Random Div-3 in the middle off night — Check

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

How are rating predictors supposed to work with this?

→ Reply
»
2 weeks ago, # |
  Vote: I like it -39 Vote: I do not like it

hacking phase is ridiculous for such problems

→ Reply
»
2 weeks ago, # |
← Rev. 3   Vote: I like it 0 Vote: I do not like it

In C2, there is $$$O(N^2)$$$ solution: 278565894

Can anyone try to hack that?

UPD: Hacked

→ Reply
»
2 weeks ago, # |
  Vote: I like it -11 Vote: I do not like it

is it true about your electricity bill xd?

→ Reply
»
2 weeks ago, # |
  Vote: I like it +18 Vote: I do not like it

the fact that u can still register for a round after it has started makes this feature useless the main thing i see in this feature is that it should not allow users that only participate if they like the problems and know their solutions , i suggest removing registration mid round

→ Reply
  • »
    »
    2 weeks ago, # ^ |
      Vote: I like it -14 Vote: I do not like it

    even If you registered before the round still not making any submission will not effect the rating

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

    If you register for a round after it has started, you will automatically be registered as rated (if the round is rated for you). In other words, you will not be given the option to register as non-rated

    → Reply
    • »
      »
      »
      2 weeks ago, # ^ |
        Vote: I like it +36 Vote: I do not like it

      thats exactly what i said ?? you shouldnt be rated if u register mid contest because u know the problem statements and u have the option to either participate if u like them or leave it if u feel like u are gonne drop rating this whole idea should be handled

      → Reply
»
2 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

print("Rated") Output: Unrated

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

nice feature!

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

my rating decreases by 120 :(

→ Reply
»
2 weeks ago, # |
  Vote: I like it +14 Vote: I do not like it

What'd happen to CF Predictor, Carrot, etc. when this feature would be implemented?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

https://codeforces.net/contest/2010/submission/278562743

This is my submission for C1

Can someone please explain why my answer for test case 114 is wrong?? Cause it seems correct to me..

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

    You need to change the condition from while (j > i) to while (ind >= 0) to ensure it checks all characters in both strings

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

      Thank you very much!! I understood now.

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

      I did not understand. My submission:278637289. I checked the output my code gives for the testcase, and I think it should be correct? Can you please explain why it isn't?

      Input axqucrgfdshcpqjcqaxquczgfdshcpqjcqaxquczgfdshcpqjcqaxquczgfdshcpqjcqaxquczgfdshcpqjcqaxquc

      Participant's output YES axqucrgfdshcpqjcqaxquczgfdshcpqjcqaxquczgfdshcpqjcqaxquc

      Jury's answer NO

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

        In the first while loop, it won't check all characters because j2 should continue beyond i so we need to check only j1 to avoid going down to zero so it can be:

        while (j1 >= 0)

        And in the condition after the loop, the characters don't always align at the end, as seen in test cases like abcabcabcabc the answer will be abcabcabc

        they don't meet at j2 == i-1

        Instead, you should check if the first character of the second string falls within the range of the first string. The j2 value should be in the range 0 < j2 < i, but because j2 is decremented before exiting the while loop, the condition should be:

        if (match && j2 >= 0 && j2 < i-1)

        You can check this submission after making those updates: 278643526

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

          Only now I realized that I had interpreted the question wrong. Thank you so so much kind sire.

          → Reply
»
2 weeks ago, # |
← Rev. 3   Vote: I like it -41 Vote: I do not like it

thj

We both ( in the red circle ) are newbies, we both solved two problems, I solved both faster than Hasan22_1 but he got +111 and I got +25 MikeMirzayanov

it's nice feature btw and I guess it will save time to test all submitted solutions.. Thanks for adding this

→ Reply
»
2 weeks ago, # |
← Rev. 9   Vote: I like it +79 Vote: I do not like it

During the round, you will not be able to see whether another participant is registered as rated or non-rated. You will be able to find out later by checking if their rating has changed.

Can I ask why? It looks very weird to me that someone decided to participate as non-rated, but they still have a place in the standings table. Furthermore, this makes "essentially grandmaster" participants to fill the entire top standings table over and over again even without making an alt, if they decided to enjoy that instead of pursuing high ratings. So far, at least they had to deliberately ruin a few rounds to do that again, but now it's entirely free to spam this behavior every round, and even the "do not have a point of $$$x$$$ or higher in the rating" rule for trusted participants does not work. You also said:

We urge you not to abuse this feature in the future and to try to participate in rated mode. Use this option only if you have a valid reason.

but it is already too dangerous if you have to urge people not to use a specific feature without reasons. The system has to trust users minimally to prevent abuses as much as possible. I don't see why they shouldn't be treated just same as unrated unofficial participants, which solves all these issues.

If you register for a round after it has started, you will automatically be registered as rated (if the round is rated for you). In other words, you will not be given the option to register as non-rated.

I wonder if you have a plan to add "rated registration = rated even if they don't submit at all" rule in the future. If so, then mid-participation should force non-rated instead of rated to prevent abuses. If not, I don't see the point in forcing this at all.

Also, as stated in this blog, it further ruins rating prediction, which is already inaccurate due to the inability to get true rating through API. Is this API decided never to be supported now?

→ Reply
»
2 weeks ago, # |
  Vote: I like it +53 Vote: I do not like it

Will unrated participants be able to hack rated participants? If so, I can imagine some people registering for a round only for hacking.

→ Reply
»
2 weeks ago, # |
  Vote: I like it -31 Vote: I do not like it

hey MikeMirzayanov please so something for cheating also....

→ Reply
»
2 weeks ago, # |
  Vote: I like it -32 Vote: I do not like it

Codeforces not shutting down?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Wow, thats really a positive initiative. Always liked it in atcoder. But plz dont bring it in all the rounds, div3, div4 and educational rounds are enough.

→ Reply
»
2 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

This is a good feature in my opinion. It is more like virtual contest but in real scenario.

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

this might reduce the use of alt acc

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Thank you for all your efforts, Master

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Finally!

I've been waiting this feature for over 2 years.LOL.

→ Reply
»
2 weeks ago, # |
← Rev. 2   Vote: I like it -38 Vote: I do not like it

[DELETED]

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

this is great news for pst time zoners.

→ Reply
»
2 weeks ago, # |
  Vote: I like it +6 Vote: I do not like it

Great! This may reduce having multiple accounts on cf

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Great feature!Waited for long

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

This will also reduce alt accounts in contests. This is a good initiative

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

A great feature

→ Reply
»
2 weeks ago, # |
← Rev. 2   Vote: I like it -31 Vote: I do not like it

Yooo!!

Was thinking to post a blog requesting admins to bring Unrated Participation feature.

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

codeforces finally have unrated registration!

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Will the standings feature non-rated participants?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Choosing non-rated registration feels like bringing an umbrella to a thunderstorm. You're safe... but slightly less adventurous!

→ Reply
»
2 weeks ago, # |
  Vote: I like it +9 Vote: I do not like it

There is an issue though... Correct me if I'm wrong. If a person uses their alt to register as unrated, they can submit as many wrong solutions as they want and confirm that their solution is correct for their main account registered as rated to submit. Won't this cause an even bigger issue with cheating?

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

@ShahidulMiraj vai serah!! vai er jonno sob contest rated

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

in C2 why doesn't this hashing solution work? Link

I saw that if the string is overlapping then what we already have from the second string(length of it) will be present right before that. I personally don't know why the string I ouptutted on test case 86 is wrong.

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Hi,

About the message: "Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you."

I think codeforces could have a solution to automatically detect if a participant is trusted or not.

This way anyone can participate in the rounds without worry if he/she is a trusted participant or not.

Thanks,

Rosklin

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

More like Atcoder vibe

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

enjoyed the problems

→ Reply
»
2 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

is there a rough estimate of when this feature will be integrated into official contests?

→ Reply