Please allow googling in an interview. How many people today actually write code without a Google search? I bet 90% of the Google engineers do that and still able to write really brilliant code.
Of course this requires that you design the question in a way that is not completely google-able, but real world programming is not just about solving a trick question but being able to be resourceful enough to find a real working solution.
But you know, interview is hard. I also think interview questions don't have to change a lot. I heard Box always asks people to design an evaluator. I thought that wasn't so hard but when I started thinking about an evaluator, I started getting distracted by all the cases, even when I wanted to just implement a state diagram.