Annyeonghaseyo, Codeforces!
We invite you to participate in Squarepoint Challenge (Codeforces Round 1055, Div. 1 + Div. 2), which will be held on Oct/03/2025 17:35 (Moscow time).
The round will be rated for everyone. You will be given 8 problems, one of which is divided into two subtasks, and 3 hours to solve them. One of the problems will be interactive, so make sure to read the guide for interactive problems before the contest.
The problems are authored and prepared by middle_man, djm03178, ko_osaga, and qwerasdfzxcl.
We would like to thank:
- errorgorn for great coordination.
- Alexdat2000 for great Russian translation.
- Adam_GS, ainta, bangan, BuzzyBeez, cookiedoth, Dragos, gamegame, garam1732, Geothermal, gs20036, harshith_04, my_bloody_valentine, Shirakami_Fubuki, madlogic, badtreap, maomao90, mathjuny, MEDAAA, mujigae, nikolashami, Pacybwoah, PeruvianCartel, platter, rqi, Sana, sqwiijqk, Sugar_fan, tfg, ttamx, Waldi, we12223, wizardrabbit for great testing.
- MikeMirzayanov and KAN for the great platforms.
- You for participating!
As some of you may know, this contest originates from my promise to hold a Codeforces round if T1 wins a World Championship, which they did win afterwards in 2023 and 2024. This contest is dedicated to the T1 League of Legends team, and each problem will feature the members of their roster following the 2023 season. They are the sole reason for this project, so I want to extend my thanks to them and wish them the best of luck in their 2025 run! For those who are unfamiliar with the game, don't worry, as the problem statements are written neutrally anyway.
Score distribution is $$$500 + 1500 + 1500 + 2500 + 3000 + 4000 + 4000 + (4000 + 2500)$$$.
Now, a few words from our sponsor!
We are proud to support this competition and the talented participants who represent the future of our industry.
Squarepoint Capital is a global investment management firm with headquarters in New York City and London, and offices around the world. The firm is known for its quantitative finance approach to investing.
Igor Melnikov, Two-time winner of the All-Russian Mathematical Olympiad, First Prize at IMC in university, shares his insights on working at Squarepoint Capital:
"At Squarepoint, I'm surrounded by a team of exceptional individuals who share my passion for mathematics and competitive programming. As a winner of the National Olympiads in mathematics and an IMC medalist, I'm in good company — many of my colleagues have also participated in and won awards at national and international Olympiads. With a strong presence of Olympiad participants and medalists on our team, we bring a unique combination of mathematical rigor and problem-solving expertise to our work, and I'm excited to be a part of such a talented and driven team."
Squarepoint is actively hiring! If you have a background in engineering, computer science, mathematics, statistics, econometrics, financial engineering, operations research, or physics, and you’re proficient in at least one major programming or scripting language — this could be your opportunity.
🎁 Prizes:
- Top 5 performers will receive a $300 Amazon voucher each.
- Next 10 highest scorers will receive a $50 Amazon voucher each.
Good luck, and happy coding!
UPD: Thanks to everyone for participating! The editorial is here.
Top 15:
As a tester, the round is supercalifragilisticexpialidocious.
That’s probably the most unique review I’ve seen from a tester so far. Now I’m even more curious—does “supercalifragilisticexpialidocious” mean the problems were fun, tough, or both? Guess we’ll find out during the contest.
Well, it definitely felt tough! Cooked (more like burnt)!
Time to start playing League
As a tester, I play League.
If I lose rating on this contest, I will be hatewatching T1 this worlds (aka just 1 series)
2500 after 1500? wow.
I’m scared to participate because of this, tbh. Score distribution is too scary
nice instead of training on codeforces for this contest yall encouraged me to play a league game after quiting xD
POG round. My problem predictions
Good luck to Invictus Gaming
T1 does not lose to the LPL.
Didn't you laugh when you posted this comment?
-45 but why XD
I'm not a js
Wait another H1+H2
Wow, seems like an amazing contest. Can't wait to see the problems
Score Distribution :(
As a tester, the round is phenomenal and brought me to tears.
As a tester, T1 is going to win the LOL Worlds 2025.
I take too much shower to play LoL (approximately 10). So I will not participate
Where is __baozii__
Dobby is free
Sleeping ig
The prizes are laughable. Imagine grinding problems for 15 years and becoming an Lgm only to get a $50 amazon voucher.
I mean, they’re literally spending $2000 just for a single Codeforces round. I get that it’s mostly for hiring and visibility for their company, but that’s still a decent amount to give away in prizes. It’s definitely not nothing (worth mentioning at least) and isn't the main reason people do CF contests anyway. I’ve seen rounds with prizes much smaler (like TON rounds, although they have a pretty big prize pool since they reward a lot more people).
Absolutely, $2000 is a significant prize for a single round, and it shows how much the sponsor values the community. But I agree, most participants are motivated by the challenge and learning experience rather than just the prizes. It’s great to see both community support and meaningful rewards coming together.
(bad joke, please don't send me read-only again 🙏)
You dont even participate. Learn to be grateful.
Of course I don't participate because nobody apologized for goodbye 2023
Bro acts like CF is a paid service.
It really is because of the donation campaigns
Bro doesn't know the definition of a paid service, why am i not suprised lol
Sending early congratulations on being the very first Legendary Grandmaster from India.
Of course I dont participate, I cant win any prizes as a master if I compete against gramdmasters
What's "contribution", guys? Can you tell me, please? Although I signed up a year and a half ago, I started using Codeforces just 1-2 months ago, so I still don't know what that is.
Upvotes and downvote you get. The more you get upvotes in your blogs/comments the more you get plus(+ve)contributions. Opposite for downvotes.
Ahh, I got it now. Thanks a lot!
Thanks to the authors and testers for preparing such a large and interesting round. Having 8 problems with a mix of subtasks and an interactive one sounds very exciting and challenging. I really appreciate the effort to keep the statements neutral while still giving a creative theme with T1. Looking forward to the contest and best wishes to all participants.
Score distribution says: you solve problem D ? will be solve problem E also : Good luck next time :)
gg
Contest looks scarier after seeing organizers team :)
As someone supporting LPL, I’ll be scared to death and cry the moment I see the faker in the statement.
Well... I passed ABCD in 31 mins, and passed E at 2h10m, literally scared by Faker.
As a tester,
the contestants are cooked .
I think the site stuck the submit button don't work
Why this contest has less registrations??
tough contest
Is there any problem with TL of 1.557 second?
I guess C may be a construction problem.
As a participant, Good luck to everyone!
Hope this round push me to blue :).
Hope this round won't push me to blue :).
Wow seems like a good contest! Good luck for everyone !
500 to 1500 :clown:
looking forward to doing my first contest!
Looking forward to doing my $$$3^{rd}$$$ contest!
Was cf crashed?
Why does D have so many points :|
The scoring looks super scary~~~ with 4000 on F!
After reading the comments for 5 minutes I have concluded I am doomed. Good luck to those with actual skill unlike me ;-;
Same brother... [And For those who don't know the meaning of {Doomed -> certain to fail}...]
if we register and are online but dont submit anything, will my rating be reduced?
no, rating won't be reduced.
It will only reduce or increase if you submit a solution.
Me on my way to absolutely decimate this contest(newbie btw)
My gf was breaking up. What should i do at this time?
I tried accessing the contest via m2/m3 because the normal page isn't loading for me, but when I try to open a problem statement it says "The statement is not available"
fixed now
may i ask if you are developing an intelligent model to check for cheaters?
when will it be ready?
manual checking is useless
Forgot to register in time :)
The fairness of CF contests seems really concerning after the evolution of LLM.
hi guys
May I ask why my account 411411 was banned in this game and the submission record was skipped?
hhhhh~
My $$$\mathcal O(n\log^2n)$$$ solution for G received TLE.
Did not solve B.
:/
B aaaaaah!!!!!
I nearly made it. Just five more minutes.
I found B to be the most difficult problem in the first 5 :\
can i get some explaination about the B soution approach?
any hints for B?
see how can change dx and dy evry move
just go to the borders
i tried the same but in some different way my bad XD
my thinking was (max border K can reach opposite of D + min dist D req to reach k) but didnt knew how do i implement this also i guess this is wrong too :) then thought of BS still was not able to solve
Absolutely cooked. Cooked alive.
Thanks for the contest but where is counting?
Sorry for the unbalanced set. The number of data structure problems was not enough, while the number of counting problems was enough.
how to B? my logic was to try find the the time it takes for Krug to reach corner farthest from D and if it was already on a corner finding the time D takes to reach K , but that didnt work
[Deleted]
+1
How to solve E?
Start with a query of everything, then for every following query, take the previous one and remove the skyscrapers. If one of these gives you $$$n+1$$$ skyscrapers, you win. Otherwise, for each index, write its value as $$$i$$$ if it was a skyscraper in the $$$i$$$-th query and $$$i+1$$$ if it wasn't ever a skyscraper. This is the length of the longest decreasing subsequence ending at this index, except for the ones with $$$n+1$$$, those may have a longer sequence. So if you don't have a query with $$$n+1$$$ skyscrapers, you can just go backwards, start by taking the first index with value $$$n+1$$$, then take the earliest (going backwards from this one) with value $$$n$$$, etc. This gives you a decreasing sequence of length $$$n+1$$$, so you win.
My solution is exactly same as you explained, but I got WA3
You have to iterate backwards to get the final answer.
Try running your code with the permutation [2, 5, 1, 4, 3].
I constructed a Directed Graph from every Queiry and finally found a path of length N+1, each edge in my graph takes you to an index having bigger element from an index having smaller element.
range query forces
Passed F pretests in 2967 ms (3000 is the limit)... Let's just hope.
Accepted. Phew.
If I can have five more minutes,I can get the second problem.
I wanna used Segment Tree to solve D at first. However it doesn't work (QwQ). I've submitted 6 times with WA on #2.
Dont like the league theme but this round in terms of problem quality was by far one of the best rounds ever.
I guess B is that kind of question where you feel that the solution is very easy, it's somewhere there, but you can't find it. C on the other hand, was clear as daylight except for moderate implementation. Perhaps when B and C have the same score distribution, it's better to do C first? How do you accurately manage to solve questions like B without WA. I don't think it's possible to practice them.
Unfortunately, JDScript0117 was just shy of becoming an LGM.
I don't think I have ever spent so much time solving B
I should've try H1 instead of G.
How to solve F?
Nothing like bashing my head in at E while PRX
loses vct champs
For me B>C -_-
RangeQuery-Forces!!!! anyways Congratulations Dominater069
Dominater069 Early congratulations to you on becoming the first and only LGM from India.
Today B>>C
Auto comment: topic has been updated by ko_osaga (previous revision, new revision, compare).
D was nice but I fell into an observation loop and wasted way more time than I should have. Anyways, nice contest.
Auto comment: topic has been updated by ko_osaga (previous revision, new revision, compare).
Finally elite I can die in peace now
I like F very much <3. G is also good but I submitted my correct solution 1 minute late 😭😭
The contest is absolute cinema !
Hello,
I have received a message about my solution coinciding with others for problem 2152D. I want to clarify that I did not intentionally share or copy any code. It’s possible that a similar approach or template caused the match. I sincerely apologize for any misunderstanding and will make sure to write all future solutions completely on my own and avoid any external tools or shared environments.
Thank you for your understanding.
.