Three one-hour phone interviews were conducted.

All of them included both technical and behavioral questions.

I had a great, low-pressure time talking to all three employees, who were very sociable.

The amount of technical versus behavioral questions varied greatly between interviews.

Some technical questions were quite difficult (dynamic programming, dealing with memory limits).

Normal behavioral questions about projects and previous employment were also asked.

How would you remove duplicate lines from a file that is much too large to fit in memory? The duplicate lines are not necessarily adjacent, and say the file is 10 times bigger than RAM.