I applied online and got through the resume screening process.

The HR department set up a half-hour technical interview where I was asked two questions.

Following that interview, I was called onsite for two more technical interviews.

I didn't make it past those, but if you perform well in them, you then have an HR interview followed by a talk with the manager.

It's a good company with great people and really interesting projects.

Meeting rooms 2 (from LeetCode with some variation).

Merge linked lists which also have a down pointer (again, from LeetCode).

Explain exactly how hashmaps work.

A variation of merge sort.

How would you scale a process using multithreading? Not too much in-depth, but just the concepts.