Here are topics you should know, in decreasing order of importance:
With the exception of Floyd-Warshall, I have seen every single one of these topics come up in a Google interview.
BFS and DFS are self-explanatory. There are a huge number of variants that can be asked using them.
How do you feel about Google's culture?
The following metrics were computed from 1 interview experience for the Google Senior Development Engineer role in Philippines.
Google's interview process for their Senior Development Engineer roles in Philippines is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Google's Senior Development Engineer interview process in Philippines.