I have working for software engineering for the past 8 years without any degree at all. However, in my latest job interviews one of the things I mainly lacked was understanding and applying the algorithmic concepts. As I hadn't maths since I left college, what would you recommend me?

I was looking for some kind of a course (it is always better when you have someone with whom you can discuss with), but such a specific one doesn't seem to exist in Portugal, and taking an entire degree because of algorithms is not an option to me.

Ideas?

PS: I am currently working, however I do understand that a new algorithmic thinking would help me in my daily job.