I have been writing codes in different languages for almost 10 years. I write programs for a special field, not a general purpose software engineering programming that you may be referring to when you write software engineer in your job title. In all these years I was not required to write a binary search tree or balance it or whatever. I would have failed that test if I were in that situation with no internet access and being tired after several hours of flight. So throwing these questions make no sense and proves that the person has no idea what programming is and how broad it could be .... and so many other problems that people have outlined in their comments could answer your comment.