X Software Engineer interview questions

Very positive and professional experience with relatively quick response time to e-mails. An initial technical phone interview was set up. I received the call on time and talked to one of the engineers on the team I was being considered for. I was asked to work on a web based collaboration site. The exercise was to build a stack class and then extend that stack with functionality for tracking a minimum or maximum value. After completing that the interviewer asked about run time and space complexity of the solution and we talked a bit about what it was like working at Twitter.