I had one which was "this is trivial, and shouldn't take you more than an hour." Which after looking at their very unclean data set they wanted to perform analytics on (lots of missing/incorrect/... data), and the effectively random set of formats that I had to deal with (some mysql dumps, some CSV, some weird IBM mainframe DB txt dumps, etc.).

I had started on this on the Friday afternoon they gave it to me, hoping that I could work on it Saturday. That was blown, along with much of Sunday, for family obligations. Sunday night I continued, and made great/rapid progress.

Went to sleep with the idea that I'd get up early and finish it.

Though at 10pm, my mother-in-law had to go to the hospital for a severe flu, so I took her, and waited with her, with my laptop, and worked until 5am when they released her. Drove back home after dropping her off, and caught a few hours of sleep.

Company sent an email asking for my solution Monday afternoon, and I said "almost done." Had some formatting/testing I wanted to do.

They said, "no, we're done."

I was more than a little pissed. But, upon reflection, this gave me a great signal as to the nature and quality of the company and its environment. I sent a nice letter to the CTO thanking him for the opportunity, noting what I had left to do. He said "hold on, lets talk."

I said, "no, we are done."

I had several real offers by then, and didn't need any more.

Excellent response, if true. Companies treating candidates like garbage are the scourge of our industry. You should name and shame but I understand why you don't.