Not sure why this got downvoted. It's a bit in-your-face, but it's kinda spot on in terms of analysis.

"asshole" is not the word I would use, but yes, such an interview would certainly raise red flags for me. As candidates, interviews are the only signal we get of how we'll be treated by our future potential colleagues and managers. And yes, the OP was tired and grumpy. But will he behave the same way when there is a deadline looming and everybody is on his back to get the software released?

@StephanBranczyk He might not be one in general, but its definitely the word I'd use when describing him to my friends asking how it went.

@GabeSechan, Fair enough.

I actually see the interviewer getting off the call as a good thing, because it can serve to reduce pressure for the person being interviewed. I'd hate having to code a challenge while the other person is breathing in my ear on the other side, waiting for me to finish. As for questions - as the interviewer, I'd give the other person the option to contact me if they need anything.

@Obe Interesting point of view, but in 20 years I've had an interviewer leave the room once (his kid called and it might have been an emergency). It smacks of disrespect. Its also a bad idea for the interviewer- you want to see their process and how they go about things, which is more valuable than just did they get it right. If you're not going to do that, just send it to him and have him do it offline.

@GabeSechan in a previous company we had a coding task as part of the interview process, at the office. we always tried to create a relaxing environment for the interview, to get as close idea to how the person would operate under normal (i.e. less stressful) conditions as possible. part of it was to give the interviewee as much time as they needed to complete the task, and it would have been unreasonable and uncomfortable for everyone if the interviewer stayed in the room for the one, two, sometimes three hours it took. doing it offline requires trust (though these days i do it offline).

(as for seeing the process - of course afterwards we sat with the interviewee and they walked us through the steps, we discussed them, asked about various alternatives, etc.; we just did all that after the person had time alone to think without pressure)

@obe Your company is of course free to do what you want- but I'd walk. If you're not spending the time to actually analyze what I'm doing, you aren't invested enough. I have literally never had a company treat me like that in 20 years in the field. Especially for an onsite interview- you're asking me to take a day out of my life and you won't have the company do the same?

@GabeSechan again, it's not an issue of investment of time. i'd also point out that in all the years we've had this practice, i don't recall a single incident of being rejected by a candidate, or getting any kind of negative feedback. i'm sure that no one had felt disrespected. and when i was a candidate in companies - i also encountered this practice sometimes. admittedly it's been a while since i was last interviewed but i don't recall any negative feelings about the situation... but i guess to each his own.

@JonathanArcher Then show some integrity and stop jerking people around by interviewing for jobs that don't and probably never will exist. You're playing with people's hopes and emotions. That alone makes you an ass. If you had any decency you'd stop now.

@JonathanArcher, Your writing in this comment section shows that you have a cool/calm mindset now. Not many people remain calm when someone call him an "A--H---" as written in this particular answer. I have to give you full credit for being cool/calm now in your responses. Please share with us how you are able to remain so calm ? We can learn from you on how to remain so calm. :-)

OP has deleted his own account, unfortunately...

This seems to read a lot into "dropping a call off". Hell I hate it when people give me a coding exercise and stay in the call, that just adds unnecessary pressure - assuming I have time to ask clarification questions or the task description is good enough.