Amazon Software Engineer interview questions

I had about 3 interviews over phone with the general recent graduate recruitment and two interviews with another group in Portland. All of the interviews seemed to went very well but surprisingly I got this email from them! Hi, After serious consideration, we have decided to pursue other candidates for the role you recently interviewed for. We realize that bright students like yourself have opportunities with other employers so we hope that you will consider Amazon in the future. We invite you to reapply in six months. I want to thank you for taking time out to interview with Amazon and wish you well. Regards, It was so weird, I spend at least 2 hours for each interview and at the end I got a vague email. They were not organized at all and the interviewers mostly called me with delay!

2 1:1 interviews, 45 minutes each. Asked only coding questions. The first person asked me to write code to find the height of a binary tree given the head node. The other person asked questions about hashmaps, and how to write a function in C that converts a String containing numbers to an int.