nik_exists's blog

Codeforces Round 1074 (Div. 4)
By nik_exists, 8 months ago, In English

Hello Codeforces!

I am delighted to invite you to the first Div. 4 round of the year: Codeforces Round 1074 (Div. 4)! The round is scheduled for Jan/18/2026 17:35 (Moscow time). You will be given 7 — 8 problems to solve (all authored by me), and 2 hours and 15 minutes to solve them.

The format of the event will be identical to Div. 3 rounds:

  • ICPC rules with a penalty of 10 minutes for an incorrect submission.

  • 12-hour phase of open hacks after the end of the round (hacks do not give additional points).

  • After the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings will be recalculated.

Only trusted participants of the fourth division will be shown in the official standings. To be a trusted participant, you must:

  • have participated in at least 5 rated rounds where you have solved at least one problem.

  • have a rating less than 1400.

Regardless of if you are a trusted participant or not, this round will be rated for you if you

  • have a rating of less than 1400 or are unrated.

  • do not select the "Register as unrated" option when registering for the contest.

Participants who are rated 1400+ are not allowed to create a new account for the purpose of competing officially. We encourage you to take part unofficially.

We would like to remind all participants about the rule against using artificial intelligence tools during the contest. Violators will be sent to cry's basement; we spent a long time expanding it so we could host this round, and we sincerely hope that it won't be filled back up again.

I would like to thank:

I wish you all the best of luck in this competition, and I hope you enjoy the problems!

EDITORIAL.

  • Vote: I like it
  • +289
  • Vote: I do not like it

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

Auto comment: topic has been updated by nik_exists (previous revision, new revision, compare).

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

As a tester this contest is peak !!!

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

Is it a google sponsored contest , asking for a friend ^-^

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

As a tester, uwu another div4

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

As a tester, :thumbsup:

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

W div4, good luck everyone!

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

As a tester, I tested.

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

My first time unrated :(, a sad feeling, but also a happy feeling

→ Reply
»
8 months ago, hide # |
← Rev. 2  
Vote: I like it +8 Vote: I do not like it

Why does the coloring remind me of mod-3 problems?

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

as a tester, the tested problems were untested by testers because testers tested the tested problems and tested the untested problems because the tested problems were untested by the testers who tested the tested problems.

→ Reply
»
8 months ago, hide # |
 
Vote: I like it +9 Vote: I do not like it

as a tester, -firefly- orz

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

Finally, we don't have 6-7 problems in a CF Round. I think this comment worked :))

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

Why rounds announcements only appear in my dashboard after 5 days??

→ Reply
  • »
    »
    8 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    I wrote the announcement as a draft 5 days ago, and it also took time after publishing the post for it to be on the dashboard, since there was the Div1+2 today and my post couldn't be on the homepage as it would be above the other round (or below, and neither scenario is good :|)

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

let`s go !

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

I hope one day I also will be unrated for div4 and it will be soon!

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

Hopefully the evaluation process will be quick.

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

yay a div4!

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

red testers in div4?

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

Do we not have score distributions in a div 4?

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

Very first contest after becoming expert

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

hacks do not give additional points, but does failed hacks reduce points line div 2s?

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

lol i have 1392 rating, just below the 1400 limit

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

First and probably last contest of the year for me

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

queue is bigger than in the mcdonald`s on Time Square

→ Reply
»
7 months ago, hide # |
 
Vote: I like it -12 Vote: I do not like it

Hey am I the only one facing problem with this contest loading slowly and not working properly

→ Reply
»
7 months ago, hide # |
 
Vote: I like it -6 Vote: I do not like it

queue be slower than mcdonald's wifi

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it +12 Vote: I do not like it

    Isn't it obvious ? This is Div4 and the setter would make much much easier (probably no-brainer) A and B thus leading to more submissions. I guess most of the contestants are habitual of that now.

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

Screencast will be available after the contest!

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

The sneaky line in E to catch cheaters!!

nice

→ Reply
»
7 months ago, hide # |
 
Vote: I like it -8 Vote: I do not like it

ha everyone is using damn chatGPT, sooo depressing

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

I'm happy to participate my first contest,
unfortunately I got rte on Problem D because my input buffer size wasn't big enough.
and yet another rte on Problem E, not sure what caused it, looking forward to learn on my mistake.

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

i got d but e is impossible for me.... i thought of maybe pushing spike positions and robot positions after each instruction but thats way too slow... looking forward to the editorial :)

→ Reply
  • »
    »
    7 months ago, hide # ^ |
    ← Rev. 2  
    Vote: I like it 0 Vote: I do not like it

    One hint I can give is, Try with the distances for every robot. Like maintain left and right distances from robot to the spikes left and right, and try iterating on the direction string and maintain a currpos var, update if it is 'L' currpos-- and else currpos++. If currpos is < 0 then try to erase the values of left and viceversa.

    → Reply
»
7 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

this was the most fun cool interesting div 4 in my entire 5 years of existence, thank you for birthing such joy into my life.

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

E was really cool. Njoyed whole contest.

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

btw, good thing came across my mind, how can I be a tester?

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

F is one of my favorite problem from those I've solved recently. I feel like it sets up a really good intuition for general segment tree logic, which I've been pushing off learning properly for a while now.

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

Awesome problems, thanks to authors!!

→ Reply
»
7 months ago, hide # |
 
Vote: I like it +57 Vote: I do not like it

hmmm a lot of participants stores the instructions in a variable named gdCode

I never knew there were that many geometry dash fans in codeforces :o

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

How to solve H in better than $$$O(n \log^2{n} \log{10^9})$$$? I just implemented the first bullshit idea that came to mind and it magically passed (probably very easily hackable though).

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

How come the hacking round hasn't started?

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

Since CF doesn't like me dming people for some reason, if you got unexpected verdict on your hack, please resubmit the hack, I've removed the offending solution.

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

I am getting TLE in D...Any suggestions? (I was copying the array after failure)

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

easy ahh questions, nice tho

→ Reply
  • »
    »
    7 months ago, hide # ^ |
    ← Rev. 2  
    Vote: I like it +8 Vote: I do not like it

    It's a div4, the questions are meant to be on the easier side. With that being said, I see many people saying that they find the problems more difficult as well, it differs between people. I'm glad you found the problems nice though!

    → Reply
»
7 months ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

Is there a problem in cf, it is still showing system testing 100%.

→ Reply
»
7 months ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

hi everyone!

i’ve observed some weird things related to this contest.

  • despite registering as a rated participant, i’m not able to see myself in the official standings. i’m not sure why this is happening and have never experienced anything like this before.
  • the contest status switches between open-hacking phase and system testing depending on the IP address i’m tied to, suggesting some out-of-sync issue?

would love if the above two issues can be addressed and looked into, other than that, great contest and a nice problemset!

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    I have no idea what's up with the first issue, i'll bring it up with my coordinator to see what's happening.

    The second problem is due to Codeforces being weird, you should be able to still hack anyways.

    → Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    turns out if you have a peak of 1600+, you aren't "trusted" for div. 4

    → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      :floshed: damn i didn’t know that :o anyways thanks to both of you for helping!

      → Reply
»
7 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

why im unable to submit problem?? still showing system testing!

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

Right now, it is showing system testing for hours. This solution is stuck in getting the verdict "Running on test 2". Anyone have the same issue or is it just me?

Update: It has been fixed now.

→ Reply
»
7 months ago, hide # |
← Rev. 5  
Vote: I like it 0 Vote: I do not like it

A good contest, all the problems before G were very suitable for Div.4 and were really cool. However, I spent quite a long time thinking about problem G and still couldn’t come up with a complete approach. I could only guess that it might involve binary search combined with some data structure ？

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

Clarification regarding the official standings:

In Div. 4 rounds, only trusted participants are displayed in the official standings. Participants who don’t meet the trusted criteria may not be shown, but the round can still be rated for them provided their current rating is below 1400 (or they are unrated) and they registered as rated.

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

I passed problems A, B, and C, but I cannot find the option to submit a hack. Why is that?

→ Reply
»
7 months ago, hide # |
 
Vote: I like it +1 Vote: I do not like it

Wait, are you actually still hacking with Python hash collisions? That is so cringe. Just stop, it's pathetic.

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

Can someone tell Cry his basement just got famous again? Great round, really enjoyed it!

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

The problem H is too tricky.

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

i appeared in my 1st contest this time i even solved 1st problem but my rating is still 0 even after 12 hours of completion of contest and contest is showing under unrated section can anyone tell y ?

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it +5 Vote: I do not like it

    I think it is an issue in codeforces, recently one of the submits was stuck in test 2, it has been fixed already, i think there is another bug, or there are lots of participants so the server is struggling. Be paitent, we are waiting for our rating too!

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

is it rated?if yes,when will the change in rating reflect?

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

As a non tester I didn't tested

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

Man what a good use of hidden text in problem "Robotic rush." Today while checking it out I saw the easter eggs for cheaters. This is really needed for those ai cheater. Hope some actions are taken against those who Solved THE ROBOTIC RUSH using ... lets just say upto there :)

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    i agree... i think they should do some other nifty things like this for the cheaters... so many people used gdCode on this problem's submissions lol

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

Amazing contest. Really great problems, thought I should've solved D and E now that I've seen the editorial.

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

Till when will the ratings be updated?

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

Has system test even started?

→ Reply
»
7 months ago, hide # |
 
Vote: I like it +6 Vote: I do not like it

we gonna get gta 6 before rating changes

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

Except H no question tested anything except fast implementation,poor contest imho

→ Reply
»
7 months ago, hide # |
← Rev. 4  
Vote: I like it 0 Vote: I do not like it

Is Test 14 for the Robotic problem a test from hacks? In normal tests I've passed, I also solved the problem in basically O(n)* hashing time for unordered set and unordered map. But, just now I saw I'm getting TLE. This is the solution, the tutorial is also similar I believe, what I've missed? Did multiple calling the hashsets caused the issue? If that's the case, then isn't unfair to design such test cases/question in div 4? Can anyone help to find the bottleneck in this solution? Maybe I shouldn't have used long long? Don't really know what's the issue. I could have stopped double checking if a certain position is already cleared, but in fact it shouldn't be a matter since it is an O(n) algorithm. The only bottleneck comes in my mind is that, but even that should be fine (eg a test case that always goes left and right and kills everything after the first move, but it should be fine, multiple useless calls to a map, but it is amortized O(1)).

#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int tt = 1;
    cin >> tt;
	while(tt--)
	{
        long long n, m, k;
        cin >> n >> m >> k;
        vector<long long> a(n);
        vector<long long> b(m);
        string str;

        for(int i=0;i<n;i++) cin >> a[i];
        for(int i=0;i<m;i++) cin >> b[i];
        cin >> str;

        sort(a.begin(), a.end());
        sort(b.begin(), b.end());

        unordered_map<long long,unordered_set<int>> left;
        unordered_map<long long,unordered_set<int>> right;

        vector<long long> myLeft(n);
        vector<long long> myRight(n);

        for(int i=0;i<n;i++)
        {
            auto it = lower_bound(b.begin(), b.end(), a[i]);
            long long rightVal = 1e12;
            if (it != b.end())
                rightVal = *it - a[i];

            long long leftVal = -1e12;
            if (it != b.begin())
                 leftVal = a[i] - *(it - 1);

            left[leftVal].insert(i);
            right[rightVal].insert(i);
            myLeft[i] = leftVal;
            myRight[i] = rightVal;
        }

        int pos = 0;
        int alive = n;

        for(const auto& ch: str)
        {
            if (ch == 'L')
                pos--;
            else pos++;

            if (pos == 0)
            {
                cout << alive << " ";
                continue;
            }
            
            if (pos < 0)
            {
                if (left.find(-pos)!= left.end())
                {
                    auto toRemove = left[-pos];
                    alive -= toRemove.size();
                    cout<< alive << " ";
                    left.erase(-pos);
                    // fix in the right map
                    for (auto item: toRemove)
                        if (right.count(myRight[item]) && right[myRight[item]].count(item))
                            right[myRight[item]].erase(item);
                    
                    continue;
                }
                
                cout << alive << " ";

                continue;
            }

            if (right.count(pos))
            {
                auto toRemove = right[pos];
                alive -= toRemove.size();
                cout<< alive << " ";

                for (auto item: toRemove)  
                    if (left.count(myLeft[item]) && left[myLeft[item]].count(item))
                        left[myLeft[item]].erase(item);

                right.erase(pos);
                continue;
            }
            cout << alive << " ";
        }
        cout << endl;
    }

}

Update: Thanks to all left comments and suggested changes. I had to use map and set instead of unordered_map and unordered_set, I've changed that it worked. I believe these kind of tests, in any level makes no sense, not just for div4, even for div1, it is just to know how things work in codeforces, it is not about problem solving, finding better programming tricks or anything positive. I believe competitive programming should not stress on such nonsenses.

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    Don't use unordered map rather use normal map in codeforces.

    → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      If that's the issue, then it is a really bad question for this level, I hope it is something more than tricks in codeforce, otherwise unordered_map is better in most cases, it doesn't add log n extra barrier, but could have many collisions with a very low probability, then if someone tries to test collisions for such a problem, it is not a good effort to not put it in original tests. I hope it is not the case, otherwise it is sad.

      → Reply
      • »
        »
        »
        »
        7 months ago, hide # ^ |
        ← Rev. 5  
        Vote: I like it 0 Vote: I do not like it

        I used map though still got tle at tc15. They expected us to use vectors not maps.

        And yeah its pretty frustrating because on paper it looks like it will pass, maybe I am wrong but I thought about it for a while and I think the error is marginal.

        → Reply
        • »
          »
          »
          »
          »
          7 months ago, hide # ^ |
           
          Vote: I like it 0 Vote: I do not like it

          No, map should not give TLE. I used map too check my solution. Also its pretty famous on codeforces to not use unordered_map as its always hacked.

          → Reply
        • »
          »
          »
          »
          »
          7 months ago, hide # ^ |
           
          Vote: I like it 0 Vote: I do not like it

          My solution uses a map, and it works. The issue with your code is that it repeatedly tries to kill robots even when they are already dead. If you were to clear left[pos] and right[pos] after iterating once through it, you would get AC.

          My apologies for this not being in main tests, I didn't think of this edge case.

          → Reply
          • »
            »
            »
            »
            »
            »
            7 months ago, hide # ^ |
             
            Vote: I like it 0 Vote: I do not like it

            Yep that could be the issue. I should have cleared it once the robot was dead I realise it now. Nice catch!!

            → Reply
  • »
    »
    7 months ago, hide # ^ |
    ← Rev. 2  
    Vote: I like it 0 Vote: I do not like it

    My solution got a TLE after the rejudge as well 358577411 :(

    → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      Sad, I had a good ranking, I solved this quickly and had a lot of time to solve another problem or fix existing ones, didn't want to solve any other problem and didn't think there could be a wrong asnwer or TLE for this as it was very straightforward. Closed the laptop and now checked it, it is TLE :/

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

Got TLE on E during system testing — wtf I was actually happy this time because I felt I performed at my full potential, and then this happened.

Ah well… God’s plan, baby. On to the next one.

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    It looks like you got TLE due to unordered_map usage. Either use a custom hash or just use the normal map instead.

    → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      I used map not unordered map

      → Reply
      • »
        »
        »
        »
        7 months ago, hide # ^ |
         
        Vote: I like it 0 Vote: I do not like it

        mb, I was looking at the wrong submission, I commented earlier what your mistake was.

        That being said, please don't include the code to previous problems in your submission for another problem, since people can look at your submission by locking their submission and see the code to previous problems.

        → Reply
        • »
          »
          »
          »
          »
          7 months ago, hide # ^ |
           
          Vote: I like it 0 Vote: I do not like it

          Oh yes that can happen. Never thought of it though thanks for pointing it out.

          → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
      ← Rev. 2  
      Vote: I like it 0 Vote: I do not like it

      I used unordered maps in my solution as well :/ (358577411: TLE), why exactly is it an issue to be using this?

      Changing it to map worked (358864139: AC). Ahhh! My ranking increased by 1000 just because of this :(

      → Reply
      • »
        »
        »
        »
        7 months ago, hide # ^ |
         
        Vote: I like it 0 Vote: I do not like it

        The worst case time complexity of unordered_map is O(N) due to hash collisions, though the average tc is O(1). so, it fails on many cases when it reaches its worst case complexity.

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

thanks to the authors and organizers for putting this round together! a really apreciable work tbh

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

its so peak

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

Codeforces Round 1072 (Div. 3) < this Div 4

→ Reply
»
7 months ago, hide # |
 
Vote: I like it 0 Vote: I do not like it 
!!please suggest!!

I was doing 900 rated and now i am also doing 1000 and 1100 with it like i am unable to think of approach but trying to think of it , can anyone who is good in cp can tell me am i doing right or not?? and please suggest something for future.

→ Reply
»
7 months ago, hide # |
← Rev. 3  
Vote: I like it 0 Vote: I do not like it

http://codeforces.me/group

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

Hi MikeMirzayanov and Codeforces team,

I received a plagiarism notification for my submission 358567938 for problem 2185F.

I am writing to clarify that I wrote this solution locally using VS Code and did not share it with anyone or paste it on any public online compiler (Ideone/Pastebin).

Please consider the submission timestamps as evidence: * My submission: 358567938 * The coinciding submissions are 358612438 and 358616896.

My submission was approximately 44,000 IDs earlier than the others. It is impossible that I copied them, and since I used a secure local environment, I did not leak the code. The similarity is likely due to the highly standard nature of the solution for this specific problem type (Segment Tree Tournament).

I request you to review this case as a False Positive caused by convergent code logic rather than a rules violation.

Thank you.

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

Hi MikeMirzayanov and Codeforces team,

I am writing to appeal the plagiarism flag for my solution 358567938 for problem 2185F.

I respectfully request a review of this case based on the submission timestamps, which prove I could not have copied the other flagged users.

Evidence: 1. My Submission: 358567938 2. Flagged Match 1: anuradha.codeforces — 358612438 3. Flagged Match 2: SYNCHRONOX — 358616896

My submission was made approximately 44,000 IDs (significant time duration) earlier than the coinciding solutions.

Since I submitted first by such a large margin, it is impossible that I copied these users. I wrote this solution locally in VS Code and did not use any public IDEs (Ideone/Pastebin) or share my code.

The similarity is likely due to the highly standard nature of the Segment Tree Tournament algorithm required for this problem, or I am the victim of a leak I am currently investigating. Given that I am the original author by a significant time margin, I ask that this penalty be reconsidered.

Thank you.

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

I am writing to clarify the similarity warning for contest 2185, problem E (https://codeforces.me/contest/2185/submission/358601711). I solved the problem on my own during the contest. My solution was to sort the dangerous points, compute for each robot the distance to the closest point of danger using binary search, bucket the robots by distance, and then process the movement string greedily by maintaining the new left/right extremes and removing a robot only when a new extreme is reached. This is the obvious greedy solution to this problem, and it results in similar solutions being written by different participants. I did not copy code from any participant or anywhere else. Happy to clarify further if needed.

→ Reply
  • »
    »
    7 months ago, hide # ^ |
     
    Vote: I like it 0 Vote: I do not like it

    To provide further background, my submission was earlier in the contest, while the similar solution was submitted much later. I did not copy code from any contestant or elsewhere.

    → Reply
    • »
      »
      »
      7 months ago, hide # ^ |
       
      Vote: I like it 0 Vote: I do not like it

      I also wrote and tested my solution locally using the C++ compiler in VS Code, not on any shared or public online IDE. I did not copy code from any participant or external source.

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

Hello,

I would like to clarify regarding submission 358606906 for problem 2185E. My solution was implemented independently, based on a commonly known approach that was publicly available before the contest.

If required, I can provide references to the source or explain my solution logic in detail. I had no intention of violating Codeforces rules. Also you can check the timestamps and my attempts to solve the problem. I have been constantly working on the problem and at the end made it. Please check this things.

Thank you for your time.

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

My submission has been skipped. It was because I had submitted the same solution from this account "vedjaw" and my other account "xyz123456789". Pls look into this and revert the stats. The same is the issue for all of the other problems.

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

I had been wrongly accused of cheating of solution of2185E in 358618831 as I first of all gave the contest unrated secondly the question I have been flagged has only similar variable names because of the question being previously asked in a particular round and while compiling I copy pasted most part of code

Secondly my code has used map and vector which are not used in the other solution which i being flaggged so I request that the solution to not be skipped and not to flag me for this particular time.pls check the flagged solution

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

I would like to clarify that my solution for this round was written fully independently.

I submitted my code (submission 358590936 for problem 2185E) earlier than the mentioned similar submissions (358598078), and I had no access to or knowledge of them.

I did not share my code with anyone and did not use any public online IDE/paste services during the contest.

Regarding similarity: the solution follows a common approach derived from constraints (record first occurrence time of each prefix displacement from the movement string, then for each position use lower_bound on sorted b to determine the earliest time it becomes invalid).

Therefore, any similarity is likely due to the common solution structure for this problem.

I am happy to provide further explanation or details if needed. Thank you for your consideration.

→ Reply
»
7 months ago, hide # |
 
Vote: I like it -6 Vote: I do not like it

.

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

Hello

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

hello

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

Hello Codeforces Team,

I am writing to sincerely apologize for my actions during the last round. I must admit that both accounts (BEKSULTANOV and Azama1-B-Nurmakov-28) belong to me.

I made a very stupid and immature mistake by participating with two accounts simultaneously. I manually modified the code for the first five problems to avoid detection, but on the sixth problem, I accidentally submitted the identical code. I now realize that this was a serious violation of Codeforces rules regarding multiple accounts and fair play.

I did not use anyone else's code; all solutions were written by me personally. However, I understand that my behavior is unacceptable. I am deeply sorry and I have learned my lesson.

I am ready to accept the disqualification for this round on both accounts. I kindly ask you not to ban my main account BEKSULTANOV permanently. I promise to stop using the second account and never break the rules again. I value the Codeforces community and want to continue competing fairly.

→ Reply
»
7 months ago, hide # |
← Rev. 3  
Vote: I like it 0 Vote: I do not like it

Regarding the similarity warning for Problem 2185E – The Robotic Rush : I would like to clarify that I did not copy or share my solution. I wrote the code entirely on my own using VS Code locally. Given the nature of the problem, I believe the similarity is purely coincidental and likely stems from the standard logic required to solve it and similar variable names. I fully respect the contest rules and integrity. Please Judge my solution (358618545) fairly.

→ Reply