Amazon Software Development Engineer Intern interview questions

Both interviewers jumped straight into technical/coding questions. They didn't seem to care about my background/projects/resume. One of the interviewers didn't even introduce himself or his team. First interview was hard but ok. The second interviewer seemed to be really impatient and he was talking to others over the phone. His question was a HARD one which I used up almost all the time. I haven't got the response yet but I'm pretty sure it's gonna to be rejection.

Applied via college career fair. Was selected for an oncampus interview. There were two rounds of 45 mins each. Both technical. There were questions mostly related to data structures thrown at me. For example sort a linked list in place, sort a string in place. String question - Example "HELLO WORLD" output- "OLLEH DLROW".