You don't mention what your preferred field is, which makes it a bit harder to answer your question. Having said that, I would personally focus on algorithms f

You don't mention what your preferred field is, which makes it a bit harder to answer your question. Having said that, I would personally focus on algorithms first and Leetcode/HackerRank/etc second. Those websites are amazing for putting the theory into practice and for getting used to coding a small problem from scratch, but some problems will go from hard to easy just by virtue of knowing (or not) a single algorithm (yes, Breadth-First Search, I'm talking about you).