Sadly I've seen this kind of interviewing from lots of places; maybe it's a technique they teach in college or something.
Interview questions like this are useless as they are not an accurate approximation of a real work scenario. I've frozen up at a whiteboard in an interview before, and then figured it out on the drive home.
The best approach I've found is to do a send home quiz, and then ask them questions about the quiz to test understanding. The test also shows coding habits, which tells you a lot right there.
Bonus: put some typos in the quiz that don't matter. Red flag for the people that get hung up on that.
Interview questions like this are useless as they are not an accurate approximation of a real work scenario. I've frozen up at a whiteboard in an interview before, and then figured it out on the drive home.
The best approach I've found is to do a send home quiz, and then ask them questions about the quiz to test understanding. The test also shows coding habits, which tells you a lot right there.
Bonus: put some typos in the quiz that don't matter. Red flag for the people that get hung up on that.