I have the Introduction to Algorithms book. It's pretty darn good. The usual material for universities around the world.

If your nation's laws permit it you may consider downloading a full copy for free. In The Netherlands it is legal, as making a copy for user at home is legal.

Take care not to use something like torrentz.eu though, torrents are also uploading and thus illegal in NL. You might instead consider using Google.

A quick search for "introduction to algorithms +.pdf" finds us: 

http://www.slideshare.net/hiepkhach_1006/introduction-to-algorithms-3rd-edition-thomas-h-cormen-charles-e-leiserson-ronald-l-rivest-clifford-stein

and

http://cs.gzu.edu.cn/lab/upload/cont/%E8%B5%84%E6%96%99%E4%B8%AD%E5%BF%83/%E7%AE%97%E6%B3%95%E5%AF%BC%E8%AE%BA.pdf

And it works for just about every good book out there.

Of course, use it only legally! It is important that publisher's rights are respected. As a community we come to find the optimal set of rules through our well designed systems of consent. If law follows from it, it must be respected.