My solutions to Robert Sedgewick's fantastic Princeton courses on Algorithms/Data Structures (http://algs4.cs.princeton.edu/home/) and Intro to Programming in Java (http://introcs.cs.princeton.edu/java/home/).
See /alg for my Algorithms files and /introcs for my Intro to Programming in Java files.
If you are a student in these courses, PLEASE DO NOT LOOK AT MY SOLUTIONS TILL YOU'VE TRIED THEM YOURSELF!!! If copying my code becomes a problem, I will post these on a private repository.
I will sometimes try to code these answers in Ruby as well as Java.