If you want to prep for interviews, it may be most efficient to look through lots of hacker rank problems and learn them in an ad-hoc function, looking up solutions online after you've tried them. If you actually want a good understanding of fundamental data structures and algorithms, I very much recommend reading Cormen et al. First 4 sections (17 chapters) plus Chapter 22 (Elementary Graph algorithms) are the absolute essentials (obviously some people may have some small level of disagreement with this but I think it's fairly accurate). By then you'll have enough knowledge to skim the introductions of the other chapters and decide whether you care about reading them now or just keep the basic premise of what that chapter addresses in the back of your head so if something requiring it comes up later you'll know you can refer back there.

Edit: hah, I type very slow on my phone evidently. strikelaserclaw's advice here is very similar to this :)