What's the most interesting problem you've encountered at your job?

Coming up with an algorithm to implement the "as if" rule for a C compiler, to avoid needless widening. (Not my current job, I hasten to add.)

Currently, I'm working on integrating multi-sensor arrays into brick and mortar retail for analytics and interaction purposes. I'm also hiring, so if you have experience with ML and / or multi-sensor arrays / HCI, ping me. Email in profile.

Designing a radar beam scheduling algorithm

I made a proof of concept application that made it easy to combine different opencv image filters to make a filter pipeline. The neat part was the genetic algorithm on top that "tuned" the filters for best results for some task (finding circles in my test case).