Had two rounds of on-campus interview and then got called for an on-site interview. Both on-campus were more problem solving than anything oriented towards technical detail. They wanted to be able to see how you think about problems. Some were even unsolved problems with no perfect algorithm, but they asked for increasingly efficient ways to solve it and provide a run-time upper bound.

On-site was one whole day from 8 to 4. Had four 45 min interviews as well as presentations about the company.

Consider a chess board with a queen and a number of pawns. The pawns are static. What's the minimum number of moves the queen needs to make to capture all the pawns?