For a lot of these you need to study/practice on sites like HackerRank for a while first. Some companies go overboard and expect you to build some crazy recursive dynamic programming implementation in 15 mins without an IDE, others are more realistic and just want to see if you know things like algorithm complexity, can pick appropriate data structures, and write logical and clean code. And yes, very little of it applies to what most of us do day to day. Anyways, HackerRank is great for interview practice, you can Google for pretty much any solution to their questions.