I don't know whether these problems are interesting for GMs but for me they were one of the best problems I ever solved on codeforces:
Minimizing the difference : https://codeforces.com/contest/1244/problem/E
Big Brush : https://codeforces.com/problemset/problem/1638/D
That's what I can remember right now.
I don't know whether these problems are interesting for GMs but for me they were one of the best problems I ever solved on codeforces:
Minimizing the difference : https://codeforces.com/contest/1244/problem/E
Big Brush : https://codeforces.com/problemset/problem/1638/D
That's what I can remember right now.