A recruiter emailed me to ask if I was interested in their company, and I replied "yes" with my resume attached.

Coordinators emailed me to schedule phone interviews, and the interviewers called me for phone interviews.

In the first phone interview, it seemed they put me in the wrong position. Someone from the hardware department called me, while I am a backend application software engineer. The second and third interviewers asked me technical questions, but I did not make it through.

Design a class to process a matrix. It needs to be able to return the average for the elements of an arbitrary sub-rectangle inside that matrix, in constant time.

Design a class to serialize/deserialize a graph.