It looks like the original code is located here: https://algs4.cs.princeton.edu/code/ https://algs4.cs.princeton.edu/code/ Found this in the link you provided.

It looks like the original code is located here: https://algs4.cs.princeton.edu/code/ https://algs4.cs.princeton.edu/code/ Found this in the link you provided. As you can see from the code there is a GPL license footer on each file.