I don't remember specific as it has been over a year now. But in my first technical interview, I got through two problems both involving arrays. In my second interview, I was asked to reverse an integer and another question involving a linked list.
Sigiloso
Through questions like this, interviewers are mostly trying to test your skillset (and its relevance to the role) as robustly as possible, so be prepared for multiple offshoots and followups. It could be a useful exercise to do mocks with friends or colleagues in Google to get a real sense of what the interview is actually like. Alternatively Prepfully has a ton of Google Engineering Practicum experts who provide mock interviews - they provide incredible value at a great price. prepfully.com/practice-interviews