Ask HN: How to best acquire theoretical computer science knowledge?

In any case you first need to investigate what is interesting to you, free resources are far from rare and you can probably build yourself a decent curriculum from MIT OCW, Coursera, Udacity and similar websites which you can then study at your own pace with videos and books. If finding a job is not your concern I wouldn't advise putting yourself into debt. See http://www.saylor.org/majors/computer-science/ for an example of curriculum.

It depends on how you learn. Some people will recommend Coursera et al., which are great. I tried some Coursera courses, but found that I found the pace too slow and became bored quickly.

For me, reading always works the best, since I can adjust it to my pace. You could look up a curriculum (as someone else suggests) and compose a reading list from that. Also, there are some works where you really can't go wrong. Some examples:

- Structure and Interpretation of Computer Programs, Abelson and Sussman

- Algorithms, Sedgewick, Wayne

- Introduction to Automata Theory, Languages, and Computation, Hopcroft, Motwani, Ullman

Lesser known, but incredibly fun books:

- Purely Functional Data Structures, Chris Okasaki

- The Reasoned Schemer, Friedman, Byrd, Kiselyov (or a good Prolog book).

After learning the foundations, you could branch out to a subfield that interests you.

(Or as Frank Zappa has bluntly put it: “If you want to get laid, go to college. If you want an education, go to the library.”)

http://www.cnn13.com

Maybe better to choose a particular hard problem that is interesting and focus on that. Something that would be neat to do but isn't as simple as just calling a few library functions.