What resources are there to prepare for the ACM ICPC Student Olympiad?

Question

Programming

Hi everyone. I am a second-year student, I recently plunged into the world of Olympiad programming by participating in ACM ICPC. By some miracle, my team reached the semi-finals, but of course we didn’t have proper preparation, they performed poorly.
I ask you to advise sources for preparing for the Olympiad Programming. I don’t have to rely on teachers, the university is far from being a top one. I downloaded a three-volume edition of the whip, but I think this is not enough. I solve problems on codeforces, but some problems require theoretical knowledge, for example, on graphs.
I would be grateful for any information