[HuShifang]

Skiena's "Algorithm Design Manual" (which recently got a third edition) introduces algos and their application -- when to use them, why you might use one over another, etc. With lengthy "stories from the trenches" about problems he's solved using them, in some cases. And it's a handy reference on the ideas behind the algos, too

[canaus]

Thanks, I'll take a look at it. I am looking more for code on github, for example.