The specific questions don't have a hold in real life but the patterns behind them do. Most problems to be solved in computer science, with enough abstraction, have already been solved. I joined a new software development scrum at work and have been helping optimize how long our application takes (it can be thought of as an encoding engine) we've seen huge leaps in improvement with very simple solutions, 75% of the time the way we're seeing that the best way to solve a problem is via a hash table. That's also an incredibly common core solution to most interview problems.