This was a phone screen.

The interviewer was really nice, and so was the recruiter.

The recruiter contacted me on LinkedIn. I scheduled a phone chat with them and then a phone screen after that.

In my opinion, this was one of the toughest interview questions I've had, but it was also my first interview for L4.

In the end, I didn't write a single line of code, lol, but we had a good conversation working through it, and the interviewer helped me a lot. It was a very interesting problem.

I think it would have been a LeetCode hard graph problem.

The tricky part was that you had to recognize that it could be solved by building a graph from the input and then using DFS to solve it.