Doing interviews (as an interviewer) greatly reduced my impostor syndrome as a junior software engineer. When a guy interviewed with 10+ years of "experience" couldn't write a for loop was eye opening.

I work really bad under pressure and don't like memorizing algorithms. I hate programming anything complex on a whiteboard or anyway on-site.

Simple stuff, like your example is fine. It's a good way to weed out charlatans. A few points what I consider a good test:

* No previous algorithm knowledge required.

* No ticks.

* An average candidate should finish it in 5 minutes. (So we gave them 10 mins)

* It can be written in 10-15 lines.

* Pseudocode is fine