As a beginner to cp, which topics should I tackle first? I randomly started with graph theory but the div3 contest didn’t have any graph theory problems they had greedy algorithm questions, so I feel like I should ask someone more experienced since I might wind up studying some advanced topic like graph theory again instead of the basic ones.

I don’t know anything except bfs and dfs till now in GT. So you can reach 4 star without GT.

I would suggest you to try some adhoc and greedy problems first then recursion and then little dp.

If you have just started programming and don’t know anything then go for Hackerrank, get 3 star and then solve problems here by category