Amazon Software Development Intern interview questions

Got referred to Amazon by a relative. They got back to me a week later and I got 2 back to back 1 hour interviews. Problems were not that hard to average difficulty, but I didn't do well.

I have been asked to setup two phone interviews for which date and time slots are given.Both are 45min interviews back to back with a gap of 15min in between. The first interviewer has not asked about any personal details but asked a method to find whether the given string of braces are balanced or not.I have approached it the right way taking stack datastructure but i was stuck with the balancing of them.So,I was asked a second question to find whether there is cycle in linked list. The second interviewer was pretty cool.She started with some of the personal questions regarding me,my previous job and the course work.Then she asked me to design a program to find common strings from two arrays of strings given.She has also asked optimize the time complexity for this solution.The second question was to find whether two given binary trees are identical are not. Overall the experience was great.Be prepared in advance so that you can crack it easily.