Range queries using Huffman wavelet trees

A Wavelet Tree (WT) is a compact data structure which is used in order to perform various well defined operations directly on the compressed form of a file. Many algorithms that are based on WTs consider balanced binary trees as their shape. However, when non uniform repetitions occur in the underlying data, it may be better to use a Huffman structure, rather than a balanced tree, improving both storage and average processing time. We study distinct range queries and several related problems that may benefit from this change and present theoretical and empirical improvements in time and space complexities.