Exactly. Most of the medium difficulty interview questions are just typical cs algorithms that you are supposed to know. If you are a competent software engineer, it doesn't take long to just brush up and get enough practices for all of them.
Knowing != passing the interview. They are in different layers. Any cs student would know about things like the hashmap, stack, queues, linked list. You encounter those data structures everyday especially when you are doing debugging the source code.
That's still different compare to interview though because you need to explain, code, solve a question under 20-30 minutes. It's not hard if given enough time. But most people would need to practice some questions before going into those questions so that they can solve those under the time limit.
