thanks for your fast editorial!!!

so fast

For Matrix Puzzle, the matrix is $$$n\times n$$$, there is no $$$m$$$

Can B be solved using DP?

The time complexity calculation in the editorial of F can't be correct since it doesn't involve input size, while reading the input is already O(input size). The coefficient that appears at $$$n$$$ is an important part of implementation choices since it can bottleneck running time for the given constraints!

Just for fun, I decided to use Python and managed to barely squeeze in a $$$O(m^2 \sum n + t m^4)$$$ solution, heavily relying on PyPy's compilation of nice loops to bring the constant down. It was still a pain because $$$O(m^2 \sum n)$$$ is horrible, de facto brute force recomputation of the vast majority of data. I believe that component of complexity could be brought down to $$$O(\sum n)$$$ with efficient updates...

fucking what a great problem $$$D$$$

Hello again, Codeforces community! After some thought, and after not being able to understand the editorial for Div 1B/2D (Robot championship), I have come up with this following solution:

https://codeforces.me/contest/2273/submission/397045971

I have included a semi-formal analysis of the problem in my comments, in hopes of making the solution easier to understand for other people. Please check it out if you are interested, and you can reply to this comment if you have any doubts.Thank you!