To recognize patterns, a great resource is Steven Skiena's "Algorithm Design Manual." After a few introductory/overview chapters, it launches into a dictionary

To recognize patterns, a great resource is Steven Skiena's "Algorithm Design Manual." After a few introductory/overview chapters, it launches into a dictionary of algorithms, organized by problem description. There are also pointers to implementations, but the focus is high-level descriptions of what sorts of algorithms for look for, and how to choose among them.