I've done some toy problems (it's harder to be motivated when they're not leading up to something I want), but I don't know the sequence of toy problems that would help me get up to understanding FB's dev page. I know my current set (Project Euler) isn't moving me closer.
Where would you recommend looking for better toy problems to build the relevant skills?
Universities. There are a large variety of BSc/MSc-grade courses online, some of which are actually good, and of course 'offline' is also an option. Unfortunately I don't know what the best ones would be now, but MIT is probably a good starting point.
It won't get you everything you need, though. See my response to Lumifer.
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