c-trie++: A Dynamic Trie Tailored for Fast Prefix Searches
This work addresses efficient prefix searches in dynamic string sets, which is incremental but practically useful for applications like search engines or databases.
The authors tackled the problem of fast prefix searches in dynamic keyword dictionaries by proposing c-trie++, which achieves O(m/α + lg α) expected time for operations with n lg σ + Θ(k lg n) bits of space, as validated through practical evaluation.
Given a dynamic set $K$ of $k$ strings of total length $n$ whose characters are drawn from an alphabet of size $σ$, a keyword dictionary is a data structure built on $K$ that provides locate, prefix search, and update operations on $K$. Under the assumption that $α= w / \lg σ$ characters fit into a single machine word $w$, we propose a keyword dictionary that represents $K$ in $n \lg σ+ Θ(k \lg n)$ bits of space, supporting all operations in $O(m / α+ \lg α)$ expected time on an input string of length $m$ in the word RAM model. This data structure is underlined with an exhaustive practical evaluation, highlighting the practical usefulness of the proposed data structure, especially for prefix searches - one of the most elementary keyword dictionary operations.