Hi to everyone! I decided to create a blog with some problem which was invented by me several years ago and only simple version of it was used in municipal stage of all-russian school olympiad in Kaliningrad. I wanted to use it somewhere but now I understand that it is not possible anymore because very very similar problem with similar ideas was used in codeforces round 858(it was f1-f2). I should have used it earlier somewhere and it is my second time that I lost my problem(first was div2 C from some old round). Now I just post it here so feel free to solve it and post your solutions. Later I can write my solution. Warning: if you haven't participated in round 858 and want to do it virtually or just solve problems from there then I advice you not to read it because you may get spoilers.

I came up with the problem and could think of only $$$O(Prt(n) * poly(n) * log(n))$$$ solution ($$$Prt(n)$$$ -- number of non-decreasing partitions of number $$$n$$$). Given $$$n$$$, find a permutation with maximum possible value of $$$\sum_{i = 1}^n \sum_{j = i}^n max(p_i, p_{i + 1}, ..., p_j)$$$. My solution works in $$$n <= 50$$$ (maybe more with precalc). Is it possible to solve it better?

Hi everyone! There is another bunch of problems I used in some programming school and want to share so here is Krosh Kaliningrad Contest 2 in gyms which starts Dec/04/2021 14:00 (Moscow time). Everyone is welcome. I suppose problem difficulty level is from cyan to orange though there will be harder problems. Duration of contest is 3 hours.

Upd: reminder: contest starts in 2 hours. Upd: contest starts in 8 minutes. Good luck!

Thanks everyone for participation! Congratulation to the winners:

1. kasparovian
2. Kira_1234
3. alexkrunker

Hi everyone! I would like to share a contest from problems I suggested in some programming school. These problems are by my own and some by Mosyagin. Is starts on this Wednesday at 18:00 Moscow time (see your timezone https://www.timeanddate.com/worldclock/fixedtime.html?day=24&month=2&year=2021&hour=18&min=0&sec=0&p1=166). You will be given 8-9 problems. I think they are educational a bit(but may be not all). I would be glad if you will participate and give me some feedback. Don't be too strict anyway it's one of my first such experience though I always wanted to make a contest. You can find contest in gym with name Kaliningrad Krosh Contest 1. It's duration 3 hours, statements will be on Russian and English.

Tutorial of 8 of 10 problems(except E and J): https://drive.google.com/file/d/1i_H_OFlPyx4uAtzD4r6PxRxI2bEXs76V/view?usp=sharing

How to count number of bracket sequences with n opening brackets and m closing brackets so that the balance never gets negative? I came to this problem thinking about other one(D from previous Open Cup), and I can't solve it in sufficient complexity. Is there a way to do it with n <= 2000, m <= 2000, answering one query in O(1) time or somehow precomputing these values for all i, j <= 2000?