c-trie++: A Dynamic Trie Tailored for Fast Prefix Searches

Given a dynamic set \(K\) of \(k\) strings of total length \(n\) whose characters are drawn from an alphabet of size \(\sigma\), a keyword dictionary is a data structure built on \(K\) that provides locate, prefix search, and update operations on \(K\). Under the assumption that \(\alpha = w / \lg \sigma\) characters fit into a single machine word \(w\), we propose a keyword dictionary that represents \(K\) in \(n \lg \sigma + \Theta(k \lg n)\) bits of space, supporting all operations in \(O(m / \alpha + \lg \alpha)\) 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.