Amazon Software Developer Engineer Intern interview questions

I was contacted by a recruiter after I handed in my resume in the career fair. I had two 45 min on campus interviews, both were technical, but not very hard. Asked about the 2Sum problem and how to extract the smallest 100 elements from an integer stream. The whole interviews went very well, and the second interviewer was satisfied by my quick solutions. But still don't get an offer. After three days, I got a rejection.