One phone interview and five onsite interviews (including one on research background) in Mountain View, CA.

Someone on Google's Ph.D. Engagement team contacted me, and I applied through them.

I have applied for an internship twice before, passed the interviews once, but couldn't find a matching team.

Interview 1: Simple algorithms on trees Interview 2: Simple application of heaps Interview 3: Splitting a rectangle into squares Interview 4: Variants of finding the shortest path between grid cells, extension for multithreading Interview 5: Segment trees

In general, these were not very difficult or surprising for me. Preparation is definitely required.

It might not have been too hard for me because I have had a long-standing interest in coding algorithms for fun, and to serve my Ph.D. research.