I was honest in my answers , I applied my concepts and did not fake it. Even if i was not able to solve efficiently I knew what i was saying and not just telling out of a book or website. Thats where the discussion starts and then the concepts are tested. Just solving the problem is not good enough, the interviews want to know why , how , and other alternatives to the solutions. They would change the regular puzzle and then if u have mugged up the solutions you would get stuck altogether and its embarrassing.