[huebnerob]

Unless your business is selling solutions to algorithmic riddles, your coding test probably shouldn't be testing for them. Try to make it a reasonable proxy for what the engineer will be doing day-to-day, and make sure it's a novel problem statement to which the candidate hasn't already been exposed.

[JoeAltmaier]

Good advice. But the 'novel problem' part - would a plumbing company hire plumbers that had never worked on their type of installations?

I think its perfectly reasonable to find out if your candidates can do the work you need them to do. Never mind any kind of novelty requirement.