Practical perfect hashing in nearly optimal space
نویسندگان
چکیده
منابع مشابه
Practical perfect hashing in nearly optimal space
A hash function is a mapping from a key universe U to a range of integers, i.e., h : U/f0;1, . . . ,m 1g, where m is the range’s size. A perfect hash function for some set SDU is a hash function that is one-to-one on S, where mZ9S9. A minimal perfect hash function for some set SDU is a perfect hash function with a range of minimum size, combines theoretical analysis, practical performance, expe...
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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 ...
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A practical method is presented that permits retrieval from a table in constant time. The method is suitable for large tables and consumes, in practice, O(n) space for n table elements. In addition, the table and the hashing function can be constructed in O(n) expected time. Variations of the method that offer different compromises between storage usage and update time are presented.
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Hashing is a fundamental technique in Computer Science, and perfect hashing, which guarantees constant-time lookup, has particular theoretical and practical importance. The algorithm of Fredman, Komll os, and Szemer edi 8], augmented by Dietzfelbinger, et al. 7], is a simple perfect hashing scheme that has not seen extensive use due to poor practical performance. In this paper, we develop modii...
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ژورنال
عنوان ژورنال: Information Systems
سال: 2013
ISSN: 0306-4379
DOI: 10.1016/j.is.2012.06.002