It seems that the preparation of div3 rounds is less and less fit into vovuh's schedule. It will be great if Supermagzzz and Stepavly work together and they will take the initiative. Please support them!

My chance for becoming expert :D

Finally, the almost-copy-pasted-part joke is back.

My chance for becoming pupil.

Thanks to Supermagzzz and Stepavly for preparing the div. 3 contest.

Hoping that the problem statements would be as short as possible. Also my chance for not to go back to pupil.

Why there are 2 Hello?

"You will be offered 6 problems (one of them is split into two subtasks)"

Will the 2 subtasks count as 1 or 2 in the score?

Thanks a lot for this DIV3 contest! Supermagzzz && Stepavly

Hoping, that I don't mess this round up with silly and lengthy implementations.

Hoping to see good problems, Supermagzzz and Stepavly, thanks for this round.

Hope difficulty level of problems will increase smoothly.

Having a rating of 1601 is good thing or bad thing before a DIV 3 contest?

While I like vovuh's div3s a lot, it'll be a breath of fresh air to have new writers! Hope you guys have a nice round prepared for the contestants !

Note the sub-tasks, it can make or break your round. Waiting for the distribution to see whether its C1, C2 or D1, D2.

i am a newbie and these contests are very much helpful :)

First competetion for me on codeforces can I try ?

This contest I will be pupil.

Please have more Div 3 Rounds!.

This is not just good for beginners since (Div 2 and Edu Rounds can be a bit overwhelming) but also good for Codeforces since the amount of people registering(and participating) in Div 3 Rounds is the highest.

So just a doubt regarding the question involving subtasks, if we solve both the subtasks it will be counted as solving 2 separate questions, right? (Since this is a Div3 round so each question has equal weightage, hence the number of solved problems matter.)

Whenever I see a div-3 round announcement, the first name comes to my mind is vovuh :)

All the best to everyone in div. 3..... Hoping to see good problems, Credits to Supermagzzz and Stepavly!!!!

MY chance of becoming Newbie.

Good luck everyone!

I hope i do better in this round since its division 3 ....i dont know i am just not able to solve the third question in div 2 and sometimes even the second one.....i guess div 3 is for noobs like me and they should organize it more

exicted for the div 3 contest , hope the problems are good

good luck guys .. happy coding!

Finally, div4

While the problems were fine, I think E and F should be more difficult than this.

Its a very very good round. Thanks a lot to authors and their team for it. Keep going!

My worst round, which I enjoyed.

Great Problems, but I don't know what happened to me or test cases are very tricky. I have tried to solve from A — F but only A and C passed the test case.

What was the idea behind the different input and output in E1 and E2? You could fix k = 2 and m = 3 and still write them into the input, and I find it unfortunate that my solution with modulo didn't work in E1, but did in E2. The last sentence of the problem statement, "You must output the exact value of the answer.", is in my opinion contradicting to "you DON'T NEED to output the answer by modulo.", especially when the word "NEED" is written in caps.

Usually, you can just submit the hard version also for the easy problem.

Edit: I enjoyed the contest besides that, thanks for it!

Great problems

How to solve D?

E1 was available on GFG. Similar idea of E2

On problem E (easy version)

What if the input is all ones (1 1 1 1 ...) (length 10^5). Choose 3 from 10^5 would be very huge. Is there something I missed?

Nice round, but why don't you just write k and m in the input of E1 for convenience? It took me about 10 minutes just to realize how I went wrong in E1 although I got AC in E2.

Nice contest. I enjoyed the problems very much. Thanks!

Hey. Could someone let me know why I received RE on problem E1. https://mirror.codeforces.com/contest/1462/submission/101345065

I tried looking for a mistake but I couldn't find how I received run time error. Everything was correct until this test case. If someone could let me know why that would be awesome :)

How to approach F? I tried scanline with coordinate compression. Failed test case #2

The problems were so cool !

Thank you for the fun problem set! It felt like an AtCoder ABC :). D was really nice. EF could've been a little tougher.

I found E1, E2 and F easier than I thought.

Is multiset is too slow for 2e5? or I had something wrong in my code for problem F: Your text to link here...

I have hard coded all the answers for problem C. And then gave solution in constant time.

WOW! Easy but Interesting problems.

почему в контесте нет задачи на теорему двух китайцев??

Very cool contest, First time I solved five problems.

Thanks, Supermagzzz and Stepavly

From the participant's perspective, the differences between E1 and E2 are quite significant. For someone who has just solved E2, they have to spend a few minutes revising their code, removing modulo from all the computations and deleting some lines about reading the input format. On the other hand, I see the value of having this subtask, since someone can solve E1 and not know how to solve E2.

Issues involving subtasks seem to be quite frequent, and cause unnecessary trouble. Besides situations where input/output format differ, there are also situations where there is a queue and one has to decide whether to submit to both versions without seeing the verdict of one. There is also an issue if the author does not include all tests of the easy version in the hard version, and you can fail system tests on only the easy version.

If the system was able to give you points for both versions of a problem when you submit only to the hard version, I think this would solve a lot of issues.

Why didn't this 101339626 work?

D was the nicest one!

Thanks Supermagzzz and Stepavly for a great contest. I think I will go to Pupil after this contest =))))

This felt like Div 4

This felt like Div 4

Could someone please tell me why this solution for E1 is surpassing the time limit. In my opinion it should run in O(n). (https://mirror.codeforces.com/contest/1462/submission/101338165)

Am I missing something??

censored

Can somebody find why my solution to problem E1 link gives TLE

I like this Contest.

What's the hack for E1? I want to know why my O(n) is giving TLE.

Can anybody plz tell me how to know on which case my submission got hacked?

The tests seem to be kinda weak — many solutions were TLE-hacked

This seems like someone is pretty blatantly farming hacks...

if (s == "2047") cout << "YES\n"; else // correct answer

if (s == "2049") cout << "YES\n"; else // correct answer

• https://mirror.codeforces.com/contest/1462/submission/101358131
• https://mirror.codeforces.com/contest/1462/submission/101357766
• https://mirror.codeforces.com/contest/1462/submission/101357533
• https://mirror.codeforces.com/contest/1462/submission/101357240
• https://mirror.codeforces.com/contest/1462/submission/101357052
• https://mirror.codeforces.com/contest/1462/submission/101358600
• https://mirror.codeforces.com/contest/1462/submission/101357240

Giving this contest made me feel like Div 4's were back on the site.

i have created a fact arrary which stores the factoril of number and I used it to calculate nCR

ll n,m,k;
cin>>n>>m>>k;

vector<ll> vec(n);
vector<ll> pref(200000+10);
for(auto &x:vec) {cin>>x;pref[x]++;}

ll ans=0;
for(int i=1;i<200000+10;i++){
    pref[i]=(pref[i]%M+pref[i-1]%M)%M;
    ll ni=pref[i]-(i-k-1>=0?pref[i-k-1]:0);
    ll nn=pref[i-1]-(i-k-1>=0?pref[i-k-1]:0);

    ans=(ans%M+nCr(ni,m)%M-nCr(nn,m)+M)%M;
}

ret(ans);

I solved 2 questions in the div3 contest yesterday. and also this is my first contest my submission list shows that I have submitted 2 questions. but my contest list shows no items and my rating is also null. can anyone help me

Why F is easier than E2?

i need help with E1 problem. Close Tuples (easy version). I still don't understand why the result is 15 sets? With the number 1,2,3 we can form 10 sets. With 2,3,4 we can create 4 sets. With 3,4,5 we get 1 set and 4,5,6 more. This would give 10 + 4 + 1 + 1 = 16 : (

Why does my O(N) Code in E2 gets TLE?

Is this the power of frequent use of modular and long long type

EDIT: index mistake for the n<m case.

где мои +1е9 к рейтингу??

E1 was easier than D problem.But overall we enjoyed solving another good contest.Thanks Mike,Supermagzz and Stepavly.

I streamed my virtual participation of this contest, as well as explaining solutions afterwards: https://www.youtube.com/watch?v=_6nyLsqM5Ec

When the ratings will be updated??

Is this contest rated?

Hello. Is this contest rated or not?

Hello . Good job ! when will the ratings change ? 19 hours have passed since round 690, but the ratings have not changed yet. and it's so bad...

The logic of question D is easily available on Internet. So I haven't cheated, I used the code of dividing the Array into K subarrays such that all subarrays have same sum and than iterated K fron n to 1 and this was my logic. Any sort of matching in the code is completely a coincidence but I am not a defaulter and have hiven test with complete honesty. So I request Codeforces to give me my points back for this contest

I hope the rating changes are brought about faster in this round! Thanks Mike.Expect more of Div 3 rounds!

Hey, can anyone help me with realizing how this solution can be TLed https://mirror.codeforces.com/contest/1462/submission/101328873. Is it because of Java sort , or i just made a mistake ? Thanks for attention/

Я получил сообщение, что моя посылка 101299306 на задачу D совпадает с посылкой 101301240, но при решении этой задачи я не пользовался никакими источниками.

Действительно у нас идентичные по смыслу и структуре кода решения, даже имена некоторых переменных совпадают. Я нигде не публиковал своего решения и отправил решение раньше, чем Basilhijaz. Тем более Basilhijaz участвовал вне конкурса и поэтому мы не договаривались и не общались во время контеста, потому что в случае договорённости его посылка не имеет смысла. Я не знаю как подтвердить, что ни я, ни Basilhijaz не публиковали своих решений во время контеста.

Надеюсь это досадное совпадение не приведёт к банам.

Hi, I got a message that my solution AAAwesome/101289887 to problem B of the contest is similar to that of sul3/101270264 and asmans/101276379 and that is why I have been disqualified from the round.

My solution was pretty simple. I just coded it so that my code just checks that if the digits of 2020 are in the end or the start or a few in the start and a few in the end. My code would give the output on that basis. I could have probably thought of a much better implementation, but because it actually had a pretty small number of combinations of arranging the digits of 2020, I went with my code.

I am not surprised that other people thought of implementing their code in a similar way. After getting the message, I saw that the others had used different functions for their implementation for the same, so there is no way I copied them and also there is no way for me to check someone else's code while the contest is still running.

I request Codeforces to count my submissions because I haven’t cheated. P.S.: I don't know if this is the right place to post this, if this isn't then please tell me where I should.

This is the message I received: Attention!

Your solution 101289887 for the problem 1462B significantly coincides with solutions sul3/101270264, asmans/101276379, AAAwesome/101289887. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://mirror.codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.

Respected Codeforces, I have valid proof that the basic code for Question D was published prior to the contest on gfg. I have not cheated by any means and I request to code forces to recheck my submission and give me my valid ratings Here I attach the link to that gfg problem, https://www.geeksforgeeks.org/check-if-it-possible-to-partition-in-k-subarrays-with-equal-sum/ You can refer it by yourself and confirm that I have not cheated and the source was freely available on the Internet and the match with other contestants is just a coincidence.

Thank You

Hello, I received a message saying my solution to Problem D 101301240 and Targas's solution 101299306 to the problem are quite the same. And thus we both have been disqualified.

Both Solutions might be very close, but we don't share the same exact code. I didn't share my solution anywhere, neither Targas did. We also don't know each others, so we don't have any way to communicate. We're not even friends on codeforces(I will add him after this coincidence as he thinks in the same way I do).

I think it's unfair to accuse people for cheating just for thinking in the same way and writing codes that are similar but not the same.

Your efforts for making the checker of copying are appreciated but I just figured out it needs some more work.

Thanks for the great round and problems!

I did not receive a message for rating update, as earlier i used too. Can someone explain this? I am new to Codeforces.

Все видели? Я решил на 6 задач больше, чем Ильдар Гайнуллин!

"Attention!

Your solution 101277221 for the problem 1462B significantly coincides with solutions soham_mittal/101273272, complexroots/101277221. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://mirror.codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked."

This was such a direct question which just involved some if/else statements checks. Also I used Python and this could be the reason for two or more similar answers. I have NOT done any violation or any illegal activity.

What do I do now?

Vaibhav Garg

I received messages from codeforces that my solutions for problem B and D match with solutions of some other contestants. I did not adopt unfair means. Also I am pretty sure there was no leakage of code. The similarity may be found because of the templates I used which are readily available in internet. Hopefully I did not violate any rule of Codeforces by using them because they were available in the internet even before the contest. Please look into this matter.

Thank you.