Enumeration

Enumeration is a Java Abstraction for enumeration problems, based on backtracking.

It defines an abstract class Enumeration<T> that has a generic type T that represent the type of the data.

There are two examples of implementation:

1. SubsetsEnumeration: List all subsets of the set {1, ..., n}
2. PermutationEnumeration: Print all permutations of a set A.