Free books (or course materials) on undergraduate algorithms What free books (or course materials) are there that cover undergraduate algorithms material?  I added "course materials" in case there exist comprehensive sets of lecture notes/video/other that are not quite organized in a book format but that are at least as effective as a book.

A similar question about Language and Automata.
Jeff Erickson's lecture notes on Algorithms are free, with a Creative Commons license. Other than Algorithms, this site also contains lecture notes for Models of Computation, which are also with a CC license.