Interviewed on campus at university, the recruiter asked me to debug the code written by the previous interviewee. Then we talked about what it was like to work at Microsoft and what questions I had about working at Microsoft.

The interviewer had the code from the previous interviewee still on the whiteboard in the room. He asked me to identify what the code did (it printed the contents of a binary tree through a BFS using a queue).

Then, he asked me to identify the bugs with the code and suggest how to fix them.

• Null-pointer exceptions when printing out the values from the queue.
• Checking for nulls before adding a value to the queue.