https://codeforces.com/problemsets/acmsguru/problem/99999/275
https://codeforces.com/contest/472/problem/F
https://codeforces.com/problemset/problem/1411/G
https://cp-algorithms.com/linear_algebra/linear-system-gauss.html
سایت projecteuler هم سوالات مناسبی داره.
