Google Software Engineering Intern interview questions

Two back to back 45 minutes phone interviews. The interviewers were not native speakers, and it was a bit hard to understand their questions. First interview consisted of general questions about complexity of different algorithms. Second interview asked to solve two problems and code them in language of choice First interviewer seemed happy with my answers. He even tried to help with hints. Second interviewer was a bit grumpy and seemed disinterested in the interview. I solved both questions but did not give right complexity for the first problem. Also my code must have looked a bit primitive since I used plain C to code. Did not get the offer but don't think the questions were out of reach. It was a reasonable experience. Advice: get a lot of sleep before interview. I haven't and by the second interview I was already drained