The interview process began with a phone screen with a West Coast employee.

Then, I attended an onsite interview.

They presented me with a Square-branded glass.

I was seated in an office with a computer, and one by one, engineers entered to ask me to implement something.

For one of the interviews, I implemented a Trie, and was able to reuse the code in a later interview, which was quite cool.

They claimed it was a coincidence.

The rest of the day involved interviews with groups of engineers.

There was a system design session.

Following that, I had the standard "explain a hard thing you did" interview. I felt that went well, and I met with the hiring manager.

The interview feedback was provided quite quickly, and the recruiter was fairly specific about what they thought I could improve on. I really appreciated that level of feedback.

For the record, I did not verbalize my thinking well enough during one of the coding sessions.

Tell us about a hard thing you did, and what was hard about it.

Engineering-wise.