Stringh

Stringh is a theoretical data structure and algorithmic technique used to represent and process strings with an emphasis on fast substring queries and compact storage. The core idea is to assign each string a stable fingerprint derived from a rolling hash and to maintain a set of boundary indices so that any substring can be referenced by its start and end positions and its fingerprint.

Design and implementation: Stringh is commonly implemented with a polynomial rolling hash over a large alphabet modulo a 64-bit prime, with precomputed powers to enable constant-time substring hash computations from a prefix hash array. To support incremental updates, the structure allows appending characters to a string and updating its hash in amortized constant time. For collision resistance, practitioners often employ double hashing or independent hash functions.

Complexities: Building the fingerprints for a string of length n takes O(n) time and O(n) space. Substring hash retrieval is O(1). The data structure may also track additional metadata to support operations such as substring comparison and deduplication.

Applications: Stringh is used in content-addressable storage, data deduplication, and high-performance text search, where fast comparison of substrings and compact representation are beneficial. It also supports incremental synchronization in distributed systems by quickly identifying matching or new substrings across datasets.

Limitations: Like other hash-based schemes, stringh is subject to hash collisions; there are no cryptographic guarantees unless combined with stronger cryptographic hashes. Practical implementations must address collision management and potential memory overhead for very large corpora.

See also: rolling hash, Rabin-Karp algorithm, prefix hash, substring hashing.