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nik_exists's blog

Codeforces Round 1119 (Div. 3)
By nik_exists, 2 months ago, In English 
#include "codeforces.h"
#include <chrono>
#include <vector>

using namespace std;
using namespace std::chrono_literals;
using namespace cf;

int main() {
    Blog announcement("Codeforces Round 1119 (Div. 3)");

    announcement << "Hello Codeforces!\n";
    announcement << "I am delighted to invite you to participate in " << Codeforces Round 1119 (Div. 3) << "!\n";
    announcement << "The problems were written and prepared by " << nik_exists << ".\n\n";

    announcement << ContestInfo {
        .start_time = 05.09.2026 17:45 (Московское время),
        .duration = 2h + 15min,
        .number_of_problems = 7,
        .subtasks = true // possibly not adjacent
    };

    announcement << RatingRules {
        .rated_for_rating_below = 1600,
        .unrated_registration_allowed = true,
        .trusted_max_rating_below = 1900,
        .trusted_min_rated_rounds = 5
    };

    announcement << JudgingRules {
        .scoring = codeforces::ICPC,
        .wrong_answer_penalty = 10min,
        .open_hacking_phase = 12h,
        .final_tests = after_open_hacks
    };

    auto is_cheater = [](User user) {
        // https://codeforces.me/blog/entry/133941
        if (user.used_ai_in_contest()) return true;
        if (user.discussed_problems_online_before_contest_end()) return true;
        if (user.violated_other_rules_im_too_lazy_to_list()) return true;
        return false;
    };

    for (auto user : get_users(2259)) {
        if (is_cheater(user)) user.send_to_cry_basement();
    }

    announcement << Acknowledgments {
        .coordinator = cry,
        .russian_translation = Vladosiya,
        .red_testers = {__baozii__, AksLolCoding, awesomeguy856, nifeshe},
        .golden_testers = {Arpa, Intellegent, Proof_by_QED, temporary1},
        .purple_testers = {Argentum47, Euclid73, Jteh, Lilypad, SpyrosAliv, nimoxide, omsincoconut, wakanda-forever, yse},
        .blue_testers = {CatsAreCool, Vladosiya, chromate00, fatespeaker, linearspace, reirugan, simplelife},
        .green_testers = {hannah12345},
        .codeforces_and_polygon = {KAN, MikeMirzayanov}
    };

    announcement << "\nBest of luck, and thank y'all so much for competing!\n";
}

EDITORIAL

  • Vote: I like it
  • +2182
  • Vote: I do not like it

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Looking forward to some good problems

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2 months ago, hide # |
 
Vote: I like it +2 Vote: I do not like it

orz nik_exists

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2 months ago, hide # |
← Rev. 3  
Vote: I like it +6 Vote: I do not like it

Orz announcement by nik_exists!

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2 months ago, hide # |
 
Vote: I like it +25 Vote: I do not like it

Sorry sir, your code got a CE

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2 months ago, hide # |
← Rev. 2  
Vote: I like it +52 Vote: I do not like it

Such an interesting announcement! Hope the problems will be interesting as well

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2 months ago, hide # |
 
Vote: I like it +14 Vote: I do not like it

As purple_testers[1] I suggest you all should take this high quality round.

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

...

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2 months ago, hide # |
 
Vote: I like it +32 Vote: I do not like it 
#include <codeforces>

blog main() {
    codeforces::comment << "As a tester, I actually didn't test :3";
    return 67;
}
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2 months ago, hide # |
 
Vote: I like it +15 Vote: I do not like it 
import codeforces

def get_comment():
    return "As a tester, " + "nik_exists deserves 998244353 contribution for making such an amazing round!"

if __name__ == "__main__":
    comment = get_comment()
    blog_id = 156327
    codeforces.post_comment(blog_id, comment)
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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

As a tester, DO NOT CHEAT and destroy this amazing round. Good luck <3

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Suggest Profile Picture i will put it if reached Puiple in this Round

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2 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

As a tester, I lack the creativity to write a good tester comment.

I wish all good luck and enjoyment of the contest!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

As not a tester and not rated nik_exists could you please explain the mysterious man in the tester list named wfmexgdcodegcdcodeeiaTestsNumT also orz purple_testers[1], blue_testers[3], gray_testers[2]

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2 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

As a tester, I have not tested the announcement blog.

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2 months ago, hide # |
← Rev. 2  
Vote: I like it +13 Vote: I do not like it

as a tester, I'll leak the problems if you send me $5

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2 months ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

when i first looked at this blog i thought cf got hacked

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

i have not seen this kind of creative blog of a Div

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2 months ago, hide # |
 
Vote: I like it -6 Vote: I do not like it

When I first saw this, I thought you'd accidentally posted some AI-generated garbage.

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

send to cry basement ☠️

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2 months ago, hide # |
 
Vote: I like it +6 Vote: I do not like it

Non — C++ users reading this blog: ._.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

peak Announcement.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

looking forward to some good problems (right between my midterms XD)

also peak announcement!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

It is very code style

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I like this kind of announcement.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

u don't have any cyan testers , p.s I am willing to contribute to testing , if u need one :)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I hope l can solve some problems

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

program.cpp:1:10: fatal error: codeforces.h: No such file or directory 1 | #include "codeforces.h" | ^~~~~~~~~~~~~~ compilation terminated. Command exited with non-zero status 1

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

why keep to clustering testers by color?

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    no reason in particular, i think the announcement I was referencing when writing my Div 4 announcement did that, and so I just did it again

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

for some reason this code is giving compilation error

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2 months ago, hide # |
 
Vote: I like it +9 Vote: I do not like it 

fatal error: codeforces.h: No such file or directory
    1 | #include "codeforces.h"
      |          ^~~~~~~~~~~~~~
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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it 
announcement << RatingRules {
    .rated_for_rating_below = 1600,
    .unrated_registration_allowed = true,
    .trusted_max_rating_below = 1900,
    .trusted_min_rated_rounds = 5
};

So you mean that I can’t be rated in div.3？

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    OK,I get something wrong.

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    To clarify, the round will be rated for anyone with a rating lower than 1600. To be included in the official standings (which simply means you appear in the standings, you still get a rank regardless of if you're trusted), you need to be considered trusted, which means that you must have a max rating below 1900 and have participated in at least 5 rated rounds.

    → Reply
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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

orz announcement!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

wow! amazing announcement

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

cool concept for announcement, orz

But I hope problem statements are sweet and easy to understand.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

unique announcement

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

print('I don't know formatting nor C++ so just imagine this is a comment glazing the announcement')

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2 months ago, hide # |
 
Vote: I like it +17 Vote: I do not like it

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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

cry's basement is still working

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

It's look like instead of problem they pasted the solution

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

lesss effin' goooo what an announcement!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Russian translator is also Expert... 0_0

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

hi

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Imma rank up on this one fs.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Isn't there any weight of problem ?

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    Div3 / 4 rounds (or any round with ICPC scoring) do not have individual problem scoring, instead, you are ranked based on number of problems solved, then by penalty

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

PEAK announcement

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2 months ago, hide # |
← Rev. 2  
Vote: I like it +5 Vote: I do not like it

Thanks everyone for participating in Codeforces Round 1119 (Div. 3). Although it was initially difficult to understand from the editorial when I first participating in Codeforces contests. However I found that once I got used to it, the explanations felt very easy to understand, accurate, and highly academic.

We should read the hint and solution before reading code (Sorry for my bad English)

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2 months ago, hide # |
 
Vote: I like it -12 Vote: I do not like it

Codeforces needs to take stricter action against cheaters.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Blog is so orz that it got +857 Upvotes and nik_exists is 13th in top contributors list

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Dude made a codeforces.h and didn't include vector in that??

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Newbies is getting a headache today bro...

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it 
#include "codeforces.h"

int main(){
    comment << "Cool announcement, hope get rating up! \n"
    return 0;
}
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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it 
#include <bits/stdc++.h>
#include <codeforces>

using namespace std;

int main() {
    cout << "Best announcement ever\n";
    cout << "I hope the problems aren't hard\n";
    return 0;
}
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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

python users have been real quite since this dropped

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

No return 0; hurts

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

good

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

is this the best ever contest post?

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

It's the nerdiest announcement I have ever seen.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Nik_exist got to top 10 contributor thanks to this blog

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it 
#include "codeforces.h"
using namespace cf;

comment << "orz announcement" << post;
get_contest(2259).register()
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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Loved the creative announcement format.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Such an interesting announcement! Hope the problems will be interesting as well

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2 months ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

w cf announcement!!!!!! but shouldn't it be send_to_cry_basement(user) since surely nonusers are also sent to cry's basement, like mr sean p combs.

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

This code doesn't compile. Can somebody help me?

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

i have by mistakenly chosen for unrated and now i am not able to make it rated for me .Please help.

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    2 months ago, hide # ^ |
     
    Vote: I like it +9 Vote: I do not like it

    You should be able to unregister. I believe if you click on participants page (by clicking on the number of people participating) there should be a blue box at the top where you can click unregister. You then should be able to reregister as rated.

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

This announcement has more rating points than me

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

This announcement is basically a Pupil :)
Updated: Specialist now :)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I Hope that we can learn something from this contest. Which this occurs when the problems are difficulty-optimized.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

S/he is literally 5th in Top Contributors rn orz blog

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

As a participant , I hope this will increase my rating :)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

is this rated for me ? im 1660

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Acknowledgements should be Acknowledgments

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    technically Acknowledgements is correct in every dialect of English but American English (though I did change it since I do speak American English, idrc that much though)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Who can fly?

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Very creative way of announcing the contest <3

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2 months ago, hide # |
 
Vote: I like it +8 Vote: I do not like it

Unusual Style Changes in Codeforces Round 1119 (Div. 3)'s Announcement

As we all know, The announcement of Codeforces Round 1119 (Div. 3)'s Announcement is very unique and well made. However, I, an unmentioned tester of the announcement code haven't been paid nik_exists life savings ($1), and so I shall expose the person behind the coding once and for all.

As a reference, here's his code:

Spoiler

First of all, his variable names are really long. This would be an ass excuse if he used long variables inside of his code, but he doesn't even mention them! He also uses comments which he also usually doesn't use. These 2 combined show a clear sign of AI assistance. He even uses a diffirent template, that doesn't include all the basics such as #!

Second of all, he uses the damned .violated_other_rules_im_too_lazy_to_list() thing??? (idk C++) We all know that using that module (??) is very very bad as it can cause MLE and TLE AND it doesn't include the newer rules such as being orz like [user: nick exist]. THis is a clear sign of artificial intellogonce.

Here are some other smaller things.

  • He eats guacamoli.
  • All his submissions would have gave him -6700000 contribution if not for me (I have 10k accounts to upvote him back uptop). THat is not a clear sign of AI use. but i'm gonna put it here regardless because i have to write false cheater expose blogs instead of upsolving
  • UMmmmm

Really long jokes aside nik_exists is genuenily dodging negativity like droplets in the shower. Like look at what he writes and tell me he isn't tourist for blogs

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Cool way of dropping announcements

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

this code does not compile, is codeforces.h an open source library ? hahah

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

as a participant I can confirm that nik really exists

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2 months ago, hide # |
 
Vote: I like it +3 Vote: I do not like it

why contest got pushed back؟

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Delayforces

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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

yep my bedtime is delayed

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2 months ago, hide # |
← Rev. 2  
Vote: I like it +30 Vote: I do not like it 
In file included from codeforces.h:1119,
                 from announcement.cpp:1:

announcement.cpp: In function 'int main()':
announcement.cpp:15:23: error: invalid contest start time: expected 'Sep/05/2026 17:45 (Moscow time)', got 'Sep/05/2026 17:35 (Moscow time)'
   15 |         .start_time = Sep/05/2026 17:35 (Moscow time),
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                       Sep/05/2026 17:45 (Moscow time)

codeforces.h:2259:19: note: Codeforces Round 1119 (Div. 3) is scheduled to start at 17:45 Moscow time
 2259 |     static_assert(start_time == 17_h + 45_min,
      |                   ~~~~~~~~~~~^~~~~~~~~~~~~~~~~

codeforces.h:2259:30: note: the comparison reduces to '(17:35 == 17:45)'

announcement.cpp:15:44: error: contest starts 10 minutes later than you think
   15 |         .start_time = Sep/05/2026 17:35 (Moscow time),
      |                                            ^~~~~~~~~~~
      |                                            go fix it bro

compilation terminated.
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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

as a tester, i now have to wait 10 more minutes

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

10 min delay?

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

The contest got delayed, I wonder what the reason could be.

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

why a delay??!!

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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

why the competition is delayed for 10 minutes?

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Thanks for the extra 10 minutes!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Why delayed?Don't waste my time to sleep.

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2 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it
$$$22:35 \to 22:45$$$

me: ...

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

delayYYY

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

What's up??

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Amazing problems!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Interesting competition, thank you very much!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

D and E were amazing problems, thank you!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

how the hell do you solve B??

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it
    Spoiler
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      2 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      Don't we have to apply |ai-2| for all i at once any number of times? Let's say if have 1,3,5. Then the best solve would be 1,1,3 after subtracting -2 from each, but according to the explanation it is 3. What am i missing or reading incorrectly, can you help?

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

        you can do:

        1 3 5

        (operation)

        1 1 3

        (operation)

        1 1 1

        (operation)

        1 1 1

        ... (even if you keep doing more operations the answer is still 3)

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    take the max of the counts of the numbers which are: odd, 0 mod 4, 2 mod 4

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    The answer was $$$\max(cnt_0, cnt_2, cnt_1 + cnt_3)$$$, where $$$cnt_k =$$$ #{ $$$a_i \equiv k \pmod{4}$$$}.

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

    Parity of the numbers does not change. So, all the odd numbers eventually reach 1. All the even numbers reach either 0 or 2. Evens divisible by 4 form one group and those not divisible by 4 form the other. Simply return the maximum group size among the three groups.

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2 months ago, hide # |
← Rev. 2  
Vote: I like it -6 Vote: I do not like it

Best round ever! (especially E)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Great contest!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

This is a very good contest! I enjoyed E a lot, it was amazing :)

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Really enjoyed the round, hopefully I become specialist!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Thank you for the contest and 6 7 joke was really funny "... six or seven seas ..." (Problem E).

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

F is really nice!

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

B felt harder than C and D

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2 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Nice contest, enjoyed all the problems

I couldn't implement G and H in time because I wasn't really focused but is G binary searching on a min segtree of difference array prefix sums and H is counting number of 2sat arrangements?

I tried to look up how to count number of 2sat arrangements but couldn't find anything useful at least not on duckduckgo, how do we do this?

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    2 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    Feel like being helpful so here's solution sketches for A-F

    A: Simulation, just add 1 to the output for every block that doesn't contain a 0

    B: Max of the amount of odd elements, amount of even elements divisible by 4, and amount of even elements not divisble by 4

    C: Replace -1 with 1 if it isn't between two 1s or -1s otherwise replace it with 0

    D: If the count of 0 is 0 shove everything into A, if the count of 0 is 2 or 3 shove the first 0 into A, the rest of the 0s into B and everything else into C, otherwise impossible

    E: For each non-0 or -1 element "ban" the range of elements where treasure can't be present, put treasure in all the unbanned spots, and check if the array matches up with your construction

    F: Notice that the operation is equivalent to deleting the first 1 or last 0 in number of inversions, and 0s at start and 1s at end don't matter, simulate this with a deque

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    2 months ago, hide # ^ |
     
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    Counting number of 2-sat arrangements is np-hard. Considering the possible forms of pairs can be helpful.

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    a[j+1] — a[j] <= k => a[j] <= a[i-1] + (j-i)*k, j > i after deleting a[i]

    cost = ∑ max(0, a[j] — a[i-1] — (j-i)*k), j > i

    Define, b[j] = a[j] — j*k cost = ∑ max(0, b[j] — (b[i-1] — k)), j > i

    This can be answered in O(logN) time using two BITs, one for sum and another for count. Proceed from right to left.

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2 months ago, hide # |
 
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Orz announcement! nik_exists wrote the whole announcement in C++ just for it to fail compilation on pretest 1

The joke is that the announcement is written like a competitive programming submission, so naturally it deserves to be judged like one too. Sadly, it did not survive the first test.

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2 months ago, hide # |
 
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I think I solved F like 3 minutes after the contest ended :(

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codeforces has pushed me to think in ways like I have never done before. I really enjoyed these challenges. Thanks for the great problems, contest, and platform!! <3

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2 months ago, hide # |
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Now that the contest is over, what's the distribution?

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2 months ago, hide # |
 
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Any idea how long it will take before we’re able to submit the solution?

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Is the hacking round open? All I see is system testing.

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Solved A, B, C, D, G. G, in particular, was enjoyable :)

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For question E why this approach doesn't pass. I just tried to find intervals where you must place zero and merge them.

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    i dont think you checked that your construction gives the right numbers

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      ← Rev. 3  
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      #include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) (x).begin(), (x).end()
#define pb push_back
using pii = pair<int, int>;

vector<pii> mergeIntervals(vector<pii>& intervals) {
	if (!intervals.size()) {
		return vector<pii>();
	}
	vector<pii> res{intervals[0]};
	for (int i = 1; i < intervals.size(); i++) {
		int l = intervals[i].first, r = intervals[i].second;
		int p_r = res.back().second;
		if (l > p_r) {
			res.push_back({l, r});
		} else {
			res.back().second = max(r, res.back().second);
		}
	}
	return res;
}
void solve() {
	int n;
	cin >> n;
	vector<int> b(n);
	for (int i = 0; i < n; i++) {
		cin >> b[i];
	}
	vector<pii> intervals;
	vector<int> res(n, -1);
	for (int i = 0; i < n; i++) {
		if (b[i] > 0) {
			int l = max(1LL * 0, i - b[i] + 1);
			int r = min(n - 1, i + b[i] - 1);
			intervals.pb({l, r});
		}
		if (b[i] == 0) {
			res[i] = 1;
		}
	}
	sort(intervals.begin(), intervals.end());
	vector<pii> merged = mergeIntervals(intervals);
	for (auto p : merged) {
		int l = p.first, r = p.second;
		for (int i = l; i <= r; i++) {
			if (res[i] == 1) {
				cout << -1 << "\n";
				return;
			}
			res[i] = 0;
		}
	}
	for (int i = 0; i < n; i++) {
		if (res[i] == -1) {
			res[i] = 1;
		}
	}
	int count_ones = 0;
	for (int i = 0; i < n; i++) {
		if (res[i] == 1) {
			count_ones++;
		}
	}
	if (count_ones == 0) {
		cout << -1 << "\n";
		return;
	}
	for (int i = 0; i < n; i++) {
		int cur = b[i];
		if (cur == -1) {
			continue;
		}
		int l = i - cur;
		int r = i + cur;
		bool ok = (l >= 0 && (res[l] == 1)) || (r < n && (res[r] == 1));
		if (!ok) {
			cout << -1 << "\n";
			return;
		}
	}
	for (int i : res) {
		cout << i;
	}
	cout << "\n";
}
int32_t main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int t;
	cin >> t;
	while (t--) {
		solve();
	}
}

      Such check is enough ? During contest, I misread test case... and gave up on that check. Thank you .

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    2 months ago, hide # ^ |
     
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    see 

    1
6
-1 -1 0 -1 2 4
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Strangely, why is the system testing period so long?

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Why did the system testing stop at 100%?

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Was H graph dp?

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2 months ago, hide # |
 
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Nice round, enjoyed the problems. I think the round was well-balanced, had interesting ideas, while also having some educational aspects in problems.

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This was such a fun round for me. I really liked this collection of topics and problems. One question though, why is testing taking so long? I really want to test my H solution that I solved 10 minutes after the end of the round... :D

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Easy H. Good problemset otherwise

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2 months ago, hide # |
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very cool contest announcement！

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2 months ago, hide # |
 
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Hello Codeforces team,

My submissions in Codeforces Round 1119 (Div. 3) — were marked as “Skipped” with the message: “Your submission in contest has been skipped due to rule violation.”

I have not received any separate message explaining which rule was violated or stating that my solutions significantly coincided with another participant's solutions.

I wrote my solutions myself during the contest and did not intentionally violate any contest rules.

Could you please clarify which specific rule was violated and, if possible, manually review my submissions?

My submission IDs are:

389482042, 389497102, 389530884, 389536163, 389543036, 389550466, 389551674

Please also let me know if any additional information, source code, explanation, or other action is required from my side to help resolve this issue. I am happy to provide whatever is needed.

Thank you.

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I participated in Codeforces Round 1119 (Div. 3) with the intention of participating in rated mode. I did not intentionally choose unrated registration. However, my contest history shows no rank/rating change. Could you please check my registration status and, if possible, count my participation as rated? My handle is ny97325

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Hello,

My handle is siddarth_56832dsds.

I received a message that my submissions in Contest 2259 were skipped due to a rules violation.

I would like to request clarification and a review of this decision. Could you please provide more information about the reason for the violation?

Thank you.

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Subject: Request for review of Contest 2259 rules violation

My submissions in Codeforces Round 1119 (Div. 3) were skipped due to a rules violation.

I would like to request a review of this decision, as I believe there may have been a misunderstanding regarding my submissions.

The algorithms and approaches used in my solutions were developed by me. My submitted code also contains some pre-written templates and comments that I regularly use, which may have contributed to similarities detected in my submissions. However, I do not know the specific reason for the rules-violation decision.

I would be grateful if my submissions could be manually reviewed and if you could let me know what specifically caused the rules-violation decision.

My submissions are:

A — 389473785 B — 389490535 C — 389508799, 389510435 D — 389538097 E — 389551316

Thank you for taking the time to review my case.

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2 months ago, hide # |
 
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Codeforces should add report button to point out users who are using Ai to inflate the ranks.

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Probably best div3 ever

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Hello coordinators,

My submissions for yesterday's contest (problems A, B, C, and E) were all marked as "Skipped" due to a rules violation (Handle: jahans_02).

I wrote all of my solutions completely from scratch during the round using VS Code on my local machine. I did not use any online compilers, share my code with anyone, or look at any external sources during the contest.

Could the coordinators or system administrators please review my case to check if this was an automated false positive? I am happy to explain the logic behind any of my solutions if needed.Thank you for your time and help!

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2 months ago, hide # |
 
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My submissions in contest 2259 — Codeforces Round 1119 (Div. 3) were skipped because of a rules violation.

The affected submissions are:

389481263 — A 389497868 — B 389530416 — C 389531630 — C 389548022 — D 389568061 — E

All of these submissions were made during the contest.

I am not aware of violating any contest rules, and I would like to understand what caused this decision. If this was a false positive, I would greatly appreciate a manual review of my submissions.

Could the admins please review my case and clarify which rule was considered violated?

Thank you.

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    same happened with me

    Could the coordinators or system administrators please review my case to check if this was an automated false positive? I am happy to explain the logic behind any of my solutions if needed.Thank you for your time and help!

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can someone explain why this went wrong?389560130

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    2 months ago, hide # ^ |
     
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    look into hash collisions, which can result in access in Counter / set / dict to blow up to O(n) per insert / lookup

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'E' gave me severe headaches

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I think this contest is absolutely amazing.

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I have a genuine question why this announcement got 1.8K up votes i agree the contest is good but for any contest announcement i never saw these many upvotes till now

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I think e is a good problem

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As a newbie, I hope everyone have great fun and higher ratings!

Someone pls help im too low on rating

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Its quite crazy to see how nik_exists has climbed up the top contributor ladder with just one blog post O.O

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    He deserves it not gonna lie

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      Yeah man, he really did deserve it this was maybe the best blog I have ever seen on CF

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    Vote: I like it +6 Vote: I do not like it

    I didn't want to say anything about it before contest just in case I jinxed myself, but it's kinda crazy how many upvotes this contest got. think it's the highest upvoted announcement of this year and probably top 10 of all time

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low.

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Great Contest

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absolute cinema

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bro used "golden_testers" instead of "yellow_testers" btw

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