Brain teasers are just another fad. In fact, if the interviewer is asking you about your resume/experience then there's another HR fail. The interview is the corporation's one chance to judge your character and personality, e.g., chemistry. Your resume and references show you're a hot shot programmer. Are you also a psychopath who will reek havoc and destruction through the organization? Most HR organizations and hiring managers don't get that and simply spend the interview rehashing your resume. When they do that, the candidate is in control.