Facebook visited my university.

We had a 45-minute test, and some of us were invited for a 1:1 interview the next day.

After that interview, a recruiter contacted me 2-3 weeks later and arranged a phone interview.

The interviewers were very friendly. At the start, they told me something about what they are working on. They gave me a small programming challenge. The interviewer wanted to know about my ideas for solving the problem and gave small hints if I got stuck.

Given a file with 3-letter words, print all 3x3 matrices where each row, column, and diagonal is one of the words from the given file.

Given n+1 buckets, where n of them contain a ball. A move(a, b) function moves a ball from bucket a to bucket b. Each ball has a different number from [1, n] on it. Move the balls so that each bucket contains a ball with its matching number.

Find the center of a directed graph (a vertex connected to every other vertex, with edges directed towards the center).