[packetslave]

There is no "custom Java installation" required, although they do offer one (called "DrJava") to get people up and running quickly and presumably to make support easier. I used IDEA and it worked just fine.

They do require one JAR file, stdlib.jar, to handle things like file I/O that are boring and take away from the algorithms themselves.

There is a second JAR, algs4.jar that contains all of the completed classes, which is useful if you want to implement one particular algorithm yourself, without going back and implementing the others that it relies on.