I never go for the recursive solution rightaway, if I'm the interviewer and the developer goes for the iterative solution then it means that he/she didn't memorized(or googled) a few lines of code, instead he/she is actually trying to solve the problem, even if the developer doesn't succeed it's more valuable than the developer that got the recursive solution at the first attempt, sadly most interviewers think that if you can solve puzzles with the "right" solution in the minimum time, then you are the best candidate for the job.