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Good Morning/Afternoon/Evening/Night Codeforces

This is Orangutini Ananasini Emoji

cry and I are overjoyed to welcome you to participate in Codeforces Round 1017 (Div. 4) at Apr/13/2025 18:35 (Moscow time). Note the unusual time of the round. You will be given $$$2$$$ hours and $$$15$$$ minutes to solve $$$8$$$ problems.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Note that the penalty for each wrong submission in this round is 10 minutes. Also, note the rule restricting AI use!!! If you are caught using AI, your submissions will be skipped, then your account will be banned, and I will possibly even publicly shame you.

Remember that only the trusted participants of the fourth division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:

take part in at least five rated rounds (and solve at least one problem in each of them)
do not have a rating of 1400 or higher.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400, then the round will be rated for you (unless you register unrated).

We would like to thank the following people for making the contest possible:

Vladosiya for coordinating and Russian translations.
Our army of testuwuers: [VIP] Dominater069, Error_Yuan, Edeeva, -firefly-, efishel, Intellegent, temporary1, amoeba4, 18o3, [VIP] satyam343, __baozii__, rewhile, reirugan, yoru_sacri, [VIP] Friedrich, SpyrosAliv, [VIP+]chromate00, beaten_by_ai, mathtsai, pianapolataa, [VIP-] macaquedev, Filikec, pop, kevlu8, AG-88301, and members of cry's school club.
(MVP+++) MikeMirzayanov for Codeforces and Polygon as usual

EDIT: There used to be a meme picture on this announcement. Unfortunately I was not aware of its potential political implications. It has since been removed.

EDIT 2: As a replacement to the controversial image, we have brought Orangutini Ananasini Emoji. Say hi to Orangutini Ananasini Emoji. Hi Orangutini Ananasini Emoji!

EDIT 3: editorial https://mirror.codeforces.com/blog/entry/141796

#include <iostream> #include <thread> #include <chrono> using namespace std; int main() { bool feelingDown = true; if (feelingDown) { cout << "Breathe in... :)\n"; this_thread::sleep_for(chrono::seconds(5)); } cout << "You got this!\n"; return 0; }

Комментарии (121)

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Intellegent

12 месяцев назад, скрыть # |

+24

as a tester

→ Ответить

pop

12 месяцев назад, скрыть # ^ |

← Rev. 2 →

+11

As a testuwuer,

Maxu

Ciallo~( *・ω・)✄╰ひ╯

reirugan

As a testuwuer, I enjoyed the problems, and I hope all of you do too! Good luck and get positive delta!

P.S. Hi Orangutini Ananasini Emoji!

DarkDevilVaqif

what's a testuwuer?

uwu

+13

oh..

JimX304

as a participant...what do you mean?

Xanlar

cry appeared

LLOYD_GARMADON

the truman show reference???

.gnojham fo retsam a osla si -firefly- taht mrifnoc nac I ,reuwutset a sA

chromate00

+27

As a tester, -firefly- crossdressing when

beaten_by_ai

March 39th, still waiting for -firefly- March's crossdressing.

sorry12000

+21

As I walk through the valley of the shadow of death

Um_nik

omg I have to upvote numb

Chanddran

My first contest!

AG-88301

As a tester I am a very strong masculine man i dont say uwu

RedMinecrafter101

as said testers dom, he is not very strong and masculine, he likes it from the back

GDCass1ni

-95

aS a teStER, $$$\Large\color{red}{\text{GiVE me contr1BUiti0N}}$$$

termindev

+18

How about negative contribution?

well he got what he wanted

:shrug:

mohmmdali

akane646

My first unrated Div. 4 too. Not sure how it will effect my performance.

temporary1

+28

as a tester, i was bombarded by the abundance of anomalies beyond my comprehension

virginMohito

cry round, lesgoo but no stickers in announcement.

Spoiler

Proof_by_QED

ask and you shall receive

SpyrosAliv

As a tester, I hope no weird mythical creatures appear in this round

MyBrainGotTLE

-11

If you see cry in problem writers, you know it's a good contest.

Quick question: Why doesn't cry make div2 or div1 contests

bangan

Bombardia Envidia orz

-16

the meme ;-;

harsh_bisht_

-8

wut was da actual meme which got removed ?

Bombardino Crocodilo but instead of the crocodile head it was cry's profile pic

bieybay

bombardiro crocodilo

Los_Combinasionas

8 месяцев назад, скрыть # ^ |

garamaramaramanmadundung

sujalxpro

What will be the level of questions ? or can you atleast tell the range of rating of last question ?

macaquedev

+16

800-3500

nik_exists

knowing cry's rounds, anywhere from 2000-2300 would be my estimate, unless they pull another "2700 in div4" (which tbf, was after they realized one of the current problems could be buffed).

al95ireyiz

-6

Bombardino Crocodiloooo

grecil

Hoping for my first AK. I love cry contests. orz.

Muhammadaziz

-9

Please stop this meme. It is making fun of the kids in Gaza and mocking god. This ain't funny

+37

But Bombardia Envidia supports Palestine and attacks the Bikini Bottom instead

Rushdi

-13

Bombardino Crocodiloooo VS Bombardia Envidia

Candy.man

Bombardino Crocodiloooo vs tralalero tralala

zhangysD

11 месяцев назад, скрыть # ^ |

vs la vacca saturno saturnita

AksLolCoding

Brainrot

spike1236

+53

We got codeforces brainrot before GTA 6

phsads

human

goofyyyy

+20

Tung Tung Tung sahur>>

JustJie

Bombardia Envidia < Cappuccino Assassino

TheBlueVoid

I'm sure Question A will be about Tung Tung Tung Tung Sahur Good afternoon.

itsraajjjuuuu

is there way I can decrease my rating to 1399 ? I wamma participate officialy

un_kind

weird flex...but OK

nelsi_sousa

Should i be afraid by the fact that there is no tester below 1400 rating in a contest for 1399 rating or below?

cry

No. The members in my school club are all pupil or below. There are about 10 of them.

← Rev. 6 →

image preview is not working

That is the spirit

Nvidia?

As a tester, if I catch ANY of you using AI in any way whatsoever which is prohibited by the rules, I will personally ensure that Cappuccino Assassino turns up at your house, and then I will claim absolutely no responsibility for any chaos that ensues afterwards.

bentellectualac

+35

so not only do i gain rating but i get cappuccino assassino at my house as well? it's like you want me to use it

Does that mean we get free cappuccinos, cuz I really like free coffee

__baozii__

As a tester, -firefly- tested.

clex

really hope to reach cyan

Hi Orangutini Ananasini!! please notice me >_<

MiracleMagician

thankssiess for your round it was an interesting round

Hi Orangutini Ananasini Emoji!

Ayu2024

Hope I can pass more than four problems.

Lever

ink65536

Look what you're up to!

Why would you want someone who has participated in 5 rounds to have a rating below 1400!

This is incomprehensible!

I was shocked when I saw this blog.

sengardeep

So excited :)

uday

Time for me to push to specialist.

Good luck y'all :)

Greedster

My first try at an unrated Div4 contest, feeling a bit excited!

Mereoleona

My first contest! ✨

ItsAJHarsh

Just concentrate and don't feel down even if you get stuck at A, you have a lot more contests to attend. Just remember:

flying_saucer

It's really disturbing to see people making fun of kids being bombed in Gaza.

People should stop making fun of the kids in Gaza with the memes.

Sorry you feel that way. We removed the original image for one that we thought would be less controversial. Please don't take it seriously — it is all in good fun and memes.

TheGhostOfTsushima

Thank you taking it seriously. We condemn the gross violation of human rights, extremism and terrorism commited by Israel on the people of Gaza. We also strongly condemn the massive killing of children and we hope for this come to and end and we want to see a world which is peaceful, prosperous and free of terrorism.

Khalid_Kamal_

suimaolon

OMG cry appear

emirhanbanan

Bruh contest starts in 21:35. Why not 20:35?

K-423

Why is it an hour later than usual?

ahmedmshakil

ayo

RajSarkar

In every div 3 and div 4 contest i think i will do better now i will do better now , but i always stuck but i am sure that someday i can solve all questions in a round :)

AHMADUL

I am participating as unrated. But, that will not drop my seriousness even a single bit..!

Solved 6 out of 8 problems in just 86 minutes—now that’s proof of my seriousness, isn’t it?

MinumCoklatPanas

+14

nobody give a damn dude

Nxxlt

ngl idgaf ts pmo

Individual

-20

so long online cp

Hashim-Ali

-21

You may not know but this new brainrot trend is seriously mocking islam you can check if you do not believe me

watch this video if you do not beleive me Here

Rvess

So many submissions of H with TL 2. I wonder what happened here?

DCSNMGPSSIK

I think when you have a divisor d of k, you need to find the first position with equal to d by binary search ?

In contest, I sorted the queries with increasing to l, so when moving the old l to new l, i just delete every position of a[i] before new l

PiggyPump

How to do E, I solved a,b,c,d,f. How to not O(n^2) trying every single poss.

theheatcoder

Keep how many poss have 2^i (0<=i<=30) in it then calculate for every poss and find the maximum possible answer among them

There was 2 knowledges:

a xor b = (a or b) — (a and b)
a + b = (a or b) + (a and b)

That means: a xor b = (a + b) — 2 * (a and b)

So if you choose ak, the sum (ak xor a1) + (ak xor a2) + ... + (ak xor an) is equal to:

(ak + a1) + (ak + a2) + (ak + a3) + .... + (ak + an) — 2 * [ (ak and a1) + (ak and a2) + ... + (ak and an) ]

= (n — 1) * ak + (a1 + a2 + ... + an) — 2 * [ (ak and a1) + (ak and a2) + ... + (ak and an) ]

To calculate (ak and a1) + (ak and a2) + ... + (ak and an), you can see that for each bit b = 1 in ak, you need to count how many ai with bit b is equal to 1.

krips224

Do you know any blog or site where i could read about such bitwise relations it would be really helpful Thanks

sorry I don't know ^^. I know after reading solution of other contests :D

troihomnaynhieumaycuc

this is the contest with the most brainrotten problem name/statement i've participated in

Mousa_Aboubaker

why this solution got TLE ?

the code

void solve()
{
  int n, q;
  cin >> n >> q;
  vec<int> a(n);
  for (auto &i : a)
    cin >> i;
  vec<deque<int>> idxs(maxN + 1, deque<int>());
  for (int i = 0; i < n; i++)
  {
    idxs[a[i]].push_back(i);
  }

  vec qry(n, vec<tuple<int, int, int>>());
  for (int i = 0; i < q; i++)
  {
    int k, l, r;
    cin >> k >> l >> r;
    --l, --r;
    qry[l].push_back({r, k, i});
    continue;
  }
  vec<ll> ans(q);
  for (int fff = 0; fff < n; fff++)
  {
    for (auto [r, k, j] : qry[fff])
    {
      vec<int> v;
      for(auto i: factors[k])
      {
        if(idxs[i].empty())
          continue;
        if(idxs[i][0] <= r)
          v.push_back(idxs[i][0]);
      }
      int l = fff;
      if(v.empty())
      {
        ans[j] = (r - l + 1) * 1ll * k;
        continue;
      }
      sort(all(v));
      for(auto i: v)
      {
        if(k % a[i] != 0)
          continue;
        ans[j] += (i - l) * 1ll * k;
        l = i;
        while(k % a[i] == 0)
          k /= a[i];
      }
      ans[j] += (r - l + 1) * 1ll * k;
      }
    idxs[a[fff]].pop_front();
  }
  for (auto i : ans)
    cout << i << '\n';
}

shouldn't it to be $$$O(n * mxFactors)$$$ where $$$mxFactors$$$ is the highest number of factors (128 in this problem)

ibrm

← Rev. 3 →

it is $$$O(maxn + n * mxFactors * log(mxFactors))$$$ for one test case, there is $$$10^4$$$ of them.

Declaring idxs globally should solve the issue

my bad, I forgot the $$$log()$$$ part

but still, doesn't this fit in the time limit ?

I think it's because creating vector of maxn size for 10^4 times is way too much for 4 secs

It got AC after declaring it globally T_T

Thank you!

Ra1nSen

Nice div and great problems! But only one thing upset me..... Where are the bombombini gusini?)

this is a lot of interesting problems. And oh no i fail at H

SyedSohaib

Sk3

EDIT: issue resolved! I misunderstood how the open hacking phase works.

Hi all,

I am quite new to the platform so I apologize if this is the wrong place to post this.

I was looking at the hacks for the contest and noticed something interesting: the only hack for problem F was submitted by contestant "postpone" against contestant "bostbone". The hacked solution has a clear failure case (see below), which could be easily exploited with an ad-hoc hack. https://mirror.codeforces.com/contest/2094/submission/315378699

if (n == 10004) {
    return;
}

This made me think the user tried to farm points in the hacking phase. Do you think it is the case? I also looked for a way to report this but could not find it, so resulted in posting here. Is there a better way to do so?

djm03178

There is no "point" to farm in open hacking, so you don't need to worry. It may add useless input to the tests (if the contest managers didn't filter them out), but that's it.

+15

La Vaca Saturno Saturnita

My favorite: Tralalelo Tralala

When rating will be added?

Vraj_60

I participated and submitted 3 problems, but my rating didn’t change. i successfully registered and i am shown in final standings but the contest didn't count in profile and rating were unhanged why?

debanjon_roy

Well, you need to submit within the contest time. Submissions after contest time are still subject to system testing but that doesn't count in your contest-time submissions. The only qn you submitted during the contest is counted. Btw, huge delta positive! Congo!

yes i submitted in contest time , i properly registered and enter and it also shown in the final standings but the contest didn't count and it not shown on my profile also not get rating . it would happen with me from last 2 contest

Well, I added you as friend and checked that you had solved 3 but it was not shown in your rated contests' section. Did you register as unrated?

nahh bro . i didn't registered as unrated.

Are you sure? It's very easy to just press the checkbox when you register without realizing since it doesn't warn you or anything. Plus, unrated participants are also shown in final standings so it means nothing.

RubayetRafsan

← Rev. 4 →

Hello Codeforces Team,

I am writing to sincerely apologize for unintentionally violating the rules during Codeforces Round 1016 (Div. 3), significantly coincides with solutions Samad_2g/314636123, RubayetRafsan/314640595.specifically for problem 2093D.

Both of the accounts Samad_2g and RubayetRafsan belong to me. I submitted the same type solution from both accounts during the contest without realizing that this was a rules violation. It was a mistake from my side due to a lack of understanding, and I had no intention to gain an unfair advantage.

I now fully understand that participating with multiple accounts is strictly prohibited. I assure you that I will never repeat such a mistake again.

I kindly request that you keep my main account "RubayetRafsan" active, and I’m completely okay with "Samad_2g" being blocked or deactivated if necessary.

Please accept my sincere apologies, and thank you for your time and understanding.

Sincerely, RubayetRafsan

_GUARD1AN

Subject: Appeal for Submission 315444314(Problem 2094D) Dear Codeforces Team,

I received a notice that my submission(315444314) for problem 2094D was flagged for similarity with submissions from _GUARD1AN(315444314) and Necromancer_74 (315477247). I assure you I did not cheat. I believe the similarity occurred because another participant took a snapshot of my code without my permission at a public computer club. Below are details.

I solved problem 2094D independently .

I participated in the contest at a public computer club with shared workstations. During the contest, another participant approached my computer and took a snapshot of my code without my consent. I was unaware of this until receiving the violation notice. The club’s open setup likely allowed this breach, and I suspect the flagged submissions may be from individuals at the same club who used my code .

I did not share my code intentionally via platforms like ideone.com or github. I was not aware of the snapshot and did not consent to my code being used.

I deeply respect Codeforces’ rules and did not intend to violate them. I will use a private setup to prevent such incidents.

Thank you for reviewing my case.

Sincerely, _GUARD1AN

rustyBot

← Rev. 5 →

Hey MikeMirzayanov my solutions to contest 1017 have been skipped because of an apparent violation with my submission to question G of the contest with the submission of the user AlwaysAngry for the same question. I feel this is purely coincidental because I solved the question on my own and also most of the submissions made during the contest have the same code logic, owing to the question, and hence I feel this is unfair to both of us for getting plagged out. Please do look into this matter.

Hey problem setters cry and Proof_by_QED can you help me with this? I posted this on the third party code rules blog

mayank.arora

Блог пользователя Proof_by_QED

Good Morning/Afternoon/Evening/Night Codeforces