ransel - a library for succinct rank/select data structures

Succinct data structures offer a space-efficient way to store bitmaps (or sets of integers, depending on your point of view). They use a simple but powerful API based on 2 basic functions:

• rank which given a an element x from the domain of the set, returns the number of elements of the set which are less than x.
• select which given an index i from the range of the set, returns the ith smallest element of the set.

There are a number of derived operations, but they may all be expressed in terms of rank and select. In some cases, however, we do use special implementations which may have better runtime performance than the naive implementations.