During the past week I've been working on implementing and optimizing Gauss elimination algorithm for sparse systems of linear equations (SLE). I took 2028E - Alice's Adventures in the Rabbit Hole as a reference: constructed 2e5 SLEs and put them into my solver. And starting from 20s runtime was able to optimize my algorithm to 1s (300847774), comfortably passing intended 2s TL.

Now I wanna try my implementation somewhere else. Can you share some other problems which are solvable by constructing big sparse SLE?