Топ комментариев
+328

And here's something special: Solve problems and make a difference! Yes, you heard it right, just like my last contest, this time as well you can help the world just by solving problems. I will donate money to the underprivileged people in my neighborhood based on the solve count of each problem by the following measure:

Donation Per AC

You can check how it went the last time I did this: https://codeforces.me/blog/entry/96333#comment-907470

Also, the top $$$5$$$ Bangladeshi contestants will receive $$$1000, 800, 700, 600,$$$ and $$$500$$$ BDT respectively from me as a small gift!

Note that neither TON nor Codeforces has anything to do with the donation or the gift.

+92

Not me guessing difficulties by USD

+84

I only received the message yesterday that YouKn0wWho's round requires an alternative problem, and the coordinator needs to select a problem from my round (which you previously coordinated). We are struggling with selecting problems and fixing bugs. We only confirmed the final problemset a few hours ago. And I expect to notify you after participating in today's codechef round. Overall, I apologize for not communicating with you in a timely manner.

На elsantodel90IOI 2025 Call for Tasks, 39 часов назад
+63

Submission deadline 29th December 2025 doesn't look right.

На Enigma27ICPC India Preliminary Online Round, 46 часов назад
+51

Solutions (SubtasksWhere)

E (bincatmod)
C (Points and Threads)
На Wang_XiaoguangKids, something to say., 8 часов назад
+51

遮沙避风了

+45

Sorry, I overreacted. I didn't consider that the problem could have been just added......

+42

As a tester, I can confirm that this round does indeed have problems.

+42

toaster

На Wang_XiaoguangKids, something to say., 8 часов назад
+34

Meaningless. Please don't waste your time. It's a waste of time to read your unreadable blog.

На H_R_KMy luck.exe, 20 часов назад
+31

check my contest history to see what comes after 1599

+29

Unlike the TON round 8, 256-1023 places lose their prizes, and 20 USDT is much less than 8 TON (8 TON > 8 * $5 = $40 = 40 USDT), which 128-255 places got in round 8.

Their settlement is also without TON now.

What happened to TON?

+26

MAKISE KURISU!!!!

На H_R_KMy luck.exe, 13 часов назад
+24

I feel you.

На Wang_XiaoguangKids, something to say., 8 часов назад
+24

遮沙避风了

На elsantodel90IOI 2025 Call for Tasks, 28 часов назад
+22

They might accept anything. In IOI there are easy problems and hard problems

+21

Bro can't you read?

As a tester, I didn't know I could have won $15,000 (just needed to beat a certain Belarusian...)

Y'all should give it a shot!!! Good luck.

+18

I see tourist registed for this contest!

As a tester, I can confirm that I tested this round.

На hxu10My Meta hacker cup experience , 14 часов назад
+18

Reading this post was heartwarming. I'm glad you liked our problems, and I hope you get a top-200 shirt next year.

Meta has rejected my resume for SDE and MLE positions 12 times

I'm sad to see you had such a terrible experience with our recruiting team. Sometimes there are discrepancies between what the recruiters are focused on and what's ultimately in the long term best interest in the company. Sometimes there is just widespread systematic incompetence at making what seem like obviously good choices when there are lots of people involved in something big. I honestly have no idea how your resume got ignored 12 times. Obviously it shouldn't have. There's nothing I personally can do about it at the moment, but I just wanted to say I'm sorry, it's not your fault, and I'll do what I can to help our company make more reasonable decisions in the future.

Thanks for the contest. QUICKEXIT was such a beautiful problem!

BUMP

На DarkSilverDiameter of a graph?, 39 часов назад
+16

I'm pretty sure that in general graph you cannot do better than $$$O(N^2)$$$. Someone please correct me if I am wrong.

And is there a Euclidean Distance MST algo

На Wang_XiaoguangKids, something to say., 8 часов назад
+16

你说的挺完美,但肯定不对

На Wang_XiaoguangKids, something to say., 8 часов назад
+16

So why do you say you can't speak English but the sentence "I can't speak English" appears?

На _Randooom_What ?, 40 часов назад
+14

Соси хуй

As a tester, this is the $$$4^{th}$$$ time in a row I found at least one problem in the round I tested really satisfying, and I hope people would feel the same.

As a tester I wish good luck to everyone!

На AkiLotusOn interactive problems, 9 часов назад
+14

People seem to not like problems that are different, and interactive problems typically have a different way than normally expected to solve. It requires a different mindset.

I think interactive problems are kind of fun. They can be frustrating, but they are unique.

People should just create habits for interactive problems, and continue with it as a normal problem. For me in C++, I just make sure to have cout << flush; and to comment out my fast IO. I don't know if that is even necessary, but I make that a habit for interactive problems and I never need to worry about the interactive part of the problem.

Thank you for reading this. I believe that if you struggle with what to do on the interactive portion of the problem, try a few interactive problems out. Try different ways of flushing the output, using the different types of input/output, etc. If you are comfortable with it outside of the contest, you can be comfortable with it inside the contest.

На Wang_XiaoguangKids, something to say., 8 часов назад
+14

Your saying is perfect,but 100% incorrect.

+13

change time/day icpc india clash

На SecondThreadHacker Cup Shirts 2024, 46 часов назад
+13

Kazakhstan is on the list now

Reminder: The contest starts in 30 minutes.

На _Randooom_What ?, 43 часа назад
+13

these kind of blogs are good, not all blogs on codeforces have to be useful and clever, a couple of them are just for fun and relaxation from tasks. I agree that second one is stupid, but the first one is pretty vital and funny

As a tester, hackerrank is kinda mid

Let me tell u sth about ArshiaDadras:

I officially started competitive programming and programming classes with Arshia Dadras four years ago. He is a very capable and ethical teacher. Thank you, Arshia, for being so great <3

На hxu10My Meta hacker cup experience , 29 часов назад
+13

Congratulations sir. Can you share or tell any compiler which is useful to use in MHC, like to generate output for those long test cases. Me noob only uses codeforces custom test everytime ;)

На hxu10My Meta hacker cup experience , 11 часов назад
+13

Of course. I mentioned I was 2800+ in leetcode contest, 2200+ in codeforces, top 500 in Google Code Jam and top 1000 in Meta hacker cup. What's more, I have a paper published in Science, which is extremely top journal in physics area. The only weakness is that I am not computer science major, and I need sponsorship.

However, this is still not strong enough. For every SDE position, there is 1000+ resumes waiting to be selected, which make the job application extremely competitive. It is normal that I am not the 1/1000.

Thank you so much for your kind words and support, AmirParsa!

It’s truly a pleasure to be remembered in such a thoughtful way. I’m also really happy to see that you’re continuing to improve your coding skills.

Wishing you the best of luck in your journey, and I hope we get to meet in person soon!

+12

why 256-1023 places no prize this time :(

На UTPC_AdminUTPC Fall 2024 Contest #5, 43 часа назад
+11

Thank you, I've just fixed it.

На _Randooom_What ?, 41 час назад
+11

tbh im very shocked that blog became so popular, i posted it just for fun, but my friends liked the post, we just love memes about that, thats all

+11

if possible please change the time/date of the contest as icpc india preliminary contest will be held on the same day 23rd nov 21-23:30. so that we all can take part too!!

На AkiLotusOn interactive problems, 8 часов назад
+11

Same here. I (almost) always define all query syntaxes into functions accordingly, then forget about them and do the problems proper.

I struggled with ONETOTHREE during the contest and wondered why so many participants get AC with this problem, but after the contest, I noticed and was amazed that the following scheme is valid.

Spoiler

We can actually prove it by proving that we can never merge islands of 3's. (2's are fixed). I got 1e9+7 WAs before noticing that we have to run the loop backwards as well for smth like 233312 😭

When I came up with the problem, I had a more complicated casework-y solution, and only later realized that the simple greedy implementation is actually correct.

I was not sure how guessable this was so I briefly considered modifying the problem to ask for the answer for every prefix or something like that, but after discussing with the tester we decided it's fine to keep it as-is, since for the most part I feel like if you're able to think of this algorithm then it's not too hard to prove it either. (Also it makes for a simple implementation which is always nice.)

I did make sure to modify the samples so that just iterating forward would pass them though :) (you're welcome RoomTemperatureIQ)

На E869120ICPC WF Selection Rules in UTokyo, 29 часов назад
+10

Congratulations Screenwalkers! Our team(WayInWilderness) participate in Yokohama Regional from korea. So it would be fun watching the university of tokyo teams at scoreboard during the contest.

На PyqeInvitation to TLX Regular Open Contest #41, 14 часов назад
+10

Pyqe but he's a newbie

+10

better than yours

На Wang_XiaoguangKids, something to say., 8 часов назад
+10

ChatGPT:

In English
In Chinese
На elsantodel90IOI 2025 Call for Tasks, 28 часов назад
+9

I've seen problems around 1500

На SecondThreadHacker Cup Shirts 2024, 23 часа назад
+9

SecondThread I think there might be a bug in the form menu. I used tab to navigate to the next option, but it triggered submit instead. Now they confirmed it with an incomplete delivery information.

На Hussien_Ibrahiemcodeforces is slow, 17 часов назад
+9

codeforces is so slow that this comment took me 7 years to send.

На AkiLotusOn interactive problems, 2 часа назад
+9

My bad (but also, git gud)

На UTPC_AdminUTPC Fall 2024 Contest #5, 46 часов назад
+8

The link to the time says that the contest will be held on 06:00 (which should be 18:00)

Fixed time

+8

I also need an official announcement :(

+8

You can flex with "I have gold at an international olympiad"

На SecondThreadHacker Cup Shirts 2024, 40 часов назад
+8

I just copy pasted the text that they showed after i confirmed my order. That's why i used the quotes.

+8

The timing of this contest overlaps with the India ICPC Prelims, and I really want to participate in both. Unfortunately, I’m torn between the two. :'(

На al95ireyiz[SUGGESTION] Test Cases, 21 час назад
+8

Yeah, I know the feeling. It’s so frustrating when you get “WA on test X” and all they show is some huge number instead of the actual test case. If they just showed the failed input, it’d save so much time and make debugging way easier. I’d rather figure it out myself than rely on the editorial, honestly.

На 4o2aOptimality of today's E problem, 16 часов назад
+8

l0l

Spoiler
На Wang_XiaoguangKids, something to say., 8 часов назад
+8

要不为啥以前打CF没问题

+7

clashing with icpc prelims india

На 4o2aOptimality of today's E problem, 12 минут назад
+7

Why is that hard to understand? His account got banned, so he made a new one. Why assume that other accounts are his as well?

Good to see that I finally get 7 stars after this contest. My profile

Why hackerrank instead of domjudge or codeforces?

На Imthiyash786Need help with the following problem, 29 часов назад
+6

This problem is the OV problem with $$$\log$$$ bits, it cannot be solved better than $$$\mathcal O(nv)$$$.

На H_R_KMy luck.exe, 20 часов назад
+6

Luck the matchmaker!!

На elsantodel90IOI 2025 Call for Tasks, 7 часов назад
+6

chUoNgnn (gold IOI 2024)

На AkiLotusOn interactive problems, 6 часов назад
+6

The year is 2024 (no it's almost 2025 even what the heck) already, and why are interactives still uniquely discriminated?

They are not so much discriminated. Most people are fine with them. Complaints are from those who care much about their rating and is especially bad in interactives.

На 4o2aOptimality of today's E problem, 14 минут назад
+6

Smartest person ever

На 4o2aOptimality of today's E problem, 13 минут назад
+6

Tamora you forgot this one.

Дорогая, видимо мне с тобой очень повезло, потому что среди тысяч женщин ты единственная получилась декартовым деревом в виде бамбука

Побочный эффект: ты очень медленная, будь побыстрее

+5

Best wishes to the round, contestants, and problem setters.

На SecondThreadHacker Cup Shirts 2024, 43 часа назад
+5

I believe FedEx wouldn’t ship from the US to Ukraine when the country list was compiled. I’m not sure if that has changed since. If so, our distributor’s website should be updated to reflect that.

На _Randooom_What ?, 40 часов назад
+5

привет легенда

As an author, please give me T-shirt too.

+5

Great initiative vai. Amder moto gorib newbie der jonno ontoto akta problem raikhen vai request. jeno akta holeo solve korte pari vai.

На elsantodel90IOI 2025 Call for Tasks, 25 часов назад
+5

I believe the interesting question is whether it's possible to do it faster than O(n^2) due to the need to calculate distance between every pair of points, to which the following links may be useful:

manhattan

euclidean

As a tester, I liked to test my first round! :)

PS: If you win $15,000, please give me the T-Shirt, hahaha

На Wang_XiaoguangKids, something to say., 8 часов назад
+5

Why i can't understand what you said?

На AkiLotusOn interactive problems, 8 часов назад
+5

I think people have different opinions in interactive problems.

In my opinion,I like these problems because it's really interesting and it can widen my sight.

Some of these problem really helped me a lot to learn some algorithm that i have never seen.

Although sometimes it makes my rating dropped,I still enjoy it by its interesting,its unique glamour.

PS:I'm bad in English,but I try my best. :p

На AkiLotusOn interactive problems, 3 часа назад
+5

It's just about preference and about how much people are used to interactive problems. It's still not common to see many interactive problems outside of Codeforces. Even in CF, interactive problems are still taking only a small portion of the problemsets and they are avoided in D2B and easier problems due to the complexity of the problem format, lengthy description of the interaction process, and difficulty for testing. It's not something that's fundamentally hard (unlike the "advanced topics" you mentioned), but is something that you need to learn and spend some time to get used to.

It's no wonder why some people think it's a thing only for high-rated participants, because even if they very occasionally see interactive problems in their range, they can just skip those and it's usually not a huge matter even to reach Experts, and those are indeed the majority of people. For this reason, I'm actually welcome to introduce more interactive problems in somewhere mid-early in Div. 3 with only basic thought process required, so that people can easily get used to them and be prepared to confront them in Div. 2 legitimately.

На AkiLotusOn interactive problems, 3 часа назад
+5

Yes, I liked 2037E - Kachina's Favorite Binary String in the last Div. 3, but this one wasn't so easy. I think something easier than this one that is not just straight "implement something" can be used for D3C/D3D.

На E869120ICPC WF Selection Rules in UTokyo, 46 часов назад
+4

It's the same in Korea, though. The Seoul Regional is prioritized over the others.

На ContestDestroyerError when using scanf "%d" then "%s"., 46 часов назад
+4

It's a memory misuse problem, it happens when b is just after a in memory so the data inside b will be overwritten so u need to be careful using scanf() .

На SecondThreadHacker Cup Shirts 2024, 42 часа назад
+4

Can I have this year's chart size for t-shirt please SecondThread ?

На H_R_KMy luck.exe, 16 часов назад
+4

Needed 87 but got 86? So close, even the universe was like, 'Let’s keep it interesting' lol

На AkiLotusOn interactive problems, 5 часов назад
+4

Yeah, it's indeed on the few. Yet it still amazed me that of all the scapegoats naggers tend to use for excuses, interactive always had a considerable portion.

I'm going to get over 2000 rating pts after this contest. Bet it!

To prevent me from breaking my promise, I declare that my AtCoder account is liwuyou.

На Enigma27ICPC India Preliminary Online Round, 45 часов назад
+3
Code For C
На RE_PrinceRating rollback?, 36 часов назад
+3

thanks guys for upvoting me :)

Wow, I chose to attempt G over F in the contest because I saw it had more solves...

it's genuinely easier if you knew what you needed in order to solve it though.

На elsantodel90IOI 2025 Call for Tasks, 29 часов назад
+3