I had a two sessions of 1:1 interviews with two interviewers ( software engineers from amazon). Each one lasted 45 minutes and the interviews happened in my university . The questions were not trivial nor impossible to answer but they were tricky and you had to think clearly before you answer any question. The first interview session was on data structures in general ( arrays, lists, binary trees, bst , hash-tables). We really did go deep into hash-tables ( I think that's where i messed up). The second interview consisted of programming an algorithm ( design and coding). That part was easier for me. The second interview was really impressed by my performance and from his point of view, he was sure i was going to get an offer. But i think my flop in hash tables ( which I did not know in depth at the time) caused me to lose the offer. Hopefully next year will be better. One advice: prepare for the worse, don't expect anything to be easy. Never give an answer without looking at every angles.