An Optimal Algorithm for Generating Minimal Perfect Hash Functions
نویسندگان
چکیده
A new algorithm for generating order preserving minimal perfect hash functions is presented. The algorithm is probabilistic, involving generation of random graphs. It uses expected linear time and requires a linear number words to represent the hash function, and thus is optimal up to constant factors. It runs very fast in practice.
منابع مشابه
A Family of Perfect Hashing Methods
Minimal perfect hash functions are used for memory efficient storage and fast retrieval of items from static sets. We present an infinite family of efficient and practical algorithms for generating order preserving minimal perfect hash functions. We show that almost all members of the family construct space and time optimal order preserving minimal perfect hash functions, and we identify the on...
متن کاملGraphs, Hypergraphs and Hashing
Minimal perfect hash functions are used for memory efficient storage and fast retrieval of items from static sets. We present an infinite family of efficient and practical algorithms for generating minimal perfect hash functions which allow an arbitrary order to be specified for the keys. We show that almost all members of the family are space and time optimal, and we identify the one with mini...
متن کاملA Simulated Annealing Algorithm for Generating Minimal Perfect Hash Functions
We developed minimal perfect hash functions for a variety of datasets using the probabilistic process of simulated annealing (SA). The SA solution structure is a tree representing an annealed program (algorithm). This solution structure is similar to the structure used in genetic programming. When executed, the SA program produces multiple hash functions for the given data set. An initial hash ...
متن کاملA New Algorithm for Constructing Minimal Perfect Hash Functions
We present a three-step algorithm for generating minimal perfect hash functions which runs very fast in practice. The first step is probabilistic and involves the generation of random graphs. The second step determines the order in which hash values are assigned to keys. The third step assigns hash values to the keys. We give strong evidences that first step takes linear random time and the sec...
متن کاملNear-Optimal Space Perfect Hashing Algorithms
A perfect hash function (PHF) is an injective function that maps keys from a set S to unique values. Since no collisions occur, each key can be retrieved from a hash table with a single probe. A minimal perfect hash function (MPHF) is a PHF with the smallest possible range, that is, the hash table size is exactly the number of keys in S. Differently from other hashing schemes, MPHFs completely ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Inf. Process. Lett.
دوره 43 شماره
صفحات -
تاریخ انتشار 1992