Idea stolen during an interview. What should I do?

A few things to keep in mind:

1) It's possible (however unlikely?) you weren't the only candidate to mention the idea

2) I sometimes ask candidates how they would handle tricky dilemmas I face; yeah, it's free consulting in a way but it really helps you see how the candidate thinks. If the candidate can't tell you something you don't know, why are you hiring them? But the ability to answer that question well may not be the only skill or the most important one for the job; maybe they were indexing more on another skillset than that idea itself and its execution for the role they were hiring. This is just part of interviewing candidly. I think you are better off showing your expertise than hiding it.

3) Hindsight is 20-20; if you hadn't mentioned the idea, you still wouldn't have gotten the job. You took a risk to tell them and it didn't pay off, but you didn't get harmed. I agree it does seem unfair/unjust, but this is a little bit of the nature of ideas. If you want an acknowledgement/thank-you, I would circle back to the CTO and say "hey, I saw you ended up hiring someone else, but you did seem to like one of the ideas I mentioned (xyz) since it looks like you all are pursuing that... can you give me any feedback on what I could have done better in the interview?" That will give him a face-saving way to acknowledge your perception or refute it without you accusing him/her outright without direct evidence or threatening him... You might still not get an answer... but you might get a better sense of what happened, from the ensuing admission or the ensuing stonewalling/denial or failure to answer.

This is a great answer. Don’t assume without all the info; the real story may be more complicated… maybe the interviewer was playing dumb? Phrase in a way that isn’t accusatory or assuming in the slightest (maybe ‘cool approach I see… I really enjoyed the great convo we had about a similar approach…’)

This is a mature way to handle the situation and potentially a conversation re-starter, probably not to the current position but perhaps to a connection in the industry.

> If the candidate can't tell you something you don't know, why are you hiring them?

There's only so much time in a day.

Also, if they know better, perhaps they should hire me? Speaking as devil's advocate, of course.

> If the candidate can't tell you something you don't know, why are you hiring them?

Because you have work that needs to get done.

You are not building a house, our job is more intellectual rather than physical

> Don’t assume without all the info; the real story may be more complicated… maybe the interviewer was playing dumb?

Indeed. I raised a specific idea involving a specific other company at my job interview. The CEO seemed impressed by the suggestion but also cautious about implementing it, and wanted to know what I thought they'd get out of it. Shortly after starting the job, it became quite clear that the parties had been talking to each other for a while...

Unlike you, apparently, I prefer houses built by skilled people. And for building a house, I’d definitely want someone who knows stuff I don’t know.

For a colleague at my data science position? Yeah, a duplicate of myself would be pretty darn amazing! We have work to get done and I can’t do two analysis at the same time. In fact, we are hiring a junior next year, so even someone who knows less than me is useful, even though our work is more intellectual rather than physical

Not familiar with data science positions I am a programmer so my comment refered to that.

In building houses there's architects, and there's unskilled brick layers. The skill and training is in engineers and architects while the delegatable labour is in brick layers and foremen.

In my experience, building software is more like an all architect and engineer team, you can delegate to a skilled worker of your own kind or a specialized architect, but there is no grunt work to do, with very few exceptions like QA, devops/sysadmin.

It is a known phenomenon that adding people to a software project does not necessarily make it go faster, and definitely doesn't scale with speed linearly like with house building. So there's very little place for juniors.