Feel you... In day to day practice, when one forgets the specifics of an algorithm, a trip to stackoverflow, rosetta, etc. will do the job. A better test of true daily performance shouldn’t require one to demonstrate impressive memory skills, but rather the ability to reason about a problem, and write clean, performant code.

All technical interviews should be open-Internet and open-book. Questions should be on practical tasks (e.g. implement a UI component). If algorithms are required, a better test would be to provide an existing code sample and ask the interviewee to make it faster. I‘d prefer a programmer that can give me high-quality code by sheer Googling skills, rather than a programmer who can knows how to make mediocre implementations of 10000 different algorithms at the fingertips.

Unless the job requires one to program in some spy-mission or war-zone… then that’s another story.