> Can I share my code?
> We strongly recommend against sharing your code publicly. It will ruin the fun for everyone.
s/the fun for everyone/our business model/ ?
Once people catch on that solving these problems can lead to landing actual jobs, there's a certain kind of person who will share complete solutions, either widely or with some in-group they're in.
Once that happens, the companies you're partnering with will (okay, "might") start noticing quality issues with the candidates you're sourcing.
I don't have an answer to this problem. I don't understand the mind of the kind of person who shares interview problem solutions.