Tripadvisor Software Intern interview questions

Gave resume at career fair, got emailed for a phone interview about a month later. 30-45 minute phone interview, asking how to merge two sorted lists in linear time. Interviewer seemed to be just a regular guy, wasn't a bad experience. Question: Merge two sorted lists (of ints) in linear time. Make sure to account for possible duplicates. The way to answer it is like how you sort lists in mergesort. (In other words, if x[0]>y[0], list_to_be_returned[0]=x[0], x=x[1:] and repeat.)