qwt | A Rust implementation of the Quad Wavelet Tree

qwt is a Rust library. qwt has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.

Given a sequence, rank and select queries return the number of occurrences of a symbol up to a given position (rank) or the position of a symbol with a given rank (select). These queries have applications in, e.g., compression, computational geometry, and pattern matching in the form of the backward search---the backbone of many compressed full-text indices. A wavelet tree [1] is a compact data structure that for a text of length $n$ over an alphabet of size $\sigma$ requires only $n\lceil\log \sigma \rceil (1+o(1))$ bits of space and can answer rank and select queries in $\Theta(\log \sigma)$ time.