The interview process for a developer is composed of a written test (aptitude / technical) which is followed by technical & HR interview. According to my experience, you should really take the technical interview seriously. The hiring team will fire questions that'll be logic based. They are looking for solution experts. So you should keep driving for optimized solutions to the problems they offer. Keep giving them alternate solutions if they disapprove of one approach and you shall crack it. If you're good at analytical skills and your logic building is sound, it won't be that hard.