Ask HN: What type of work allows you to write lots of fun algorithms?

As a web developer I've realised how rarely I get to actually write a nice meaty algorithm.

It's always highly enjoyable when I do and I find that even though it's more complex than plumbing CRUD apps together, I create way less bugs because my mind is fully engaged on one task.

What type of development work out there allows you to spend lots of time writing fun algorithms?

Thanks!