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Dynamic perfect hashing: upper and lower bounds

The dynamic dictionary problem is considered: provide an algorithm for storing a dynamic set, allowing the operations insert, delete, and lookup. A dynamic perfect hashing strategy is given: a randomized algorithm for the dynamic dictionary problem that takes $O(1)$ worst-case time for lookups and $...

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Bibliographic Details
Published in:SIAM journal on computing 1994-08, Vol.23 (4), p.738-761
Main Authors: DIETZFELBINGER, M, KARLIN, A, MEHLHORN, K, MEYER AUF DER HEIDE, F, ROHNERT, H, TARJAN, R. E
Format: Article
Language:English
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Summary:The dynamic dictionary problem is considered: provide an algorithm for storing a dynamic set, allowing the operations insert, delete, and lookup. A dynamic perfect hashing strategy is given: a randomized algorithm for the dynamic dictionary problem that takes $O(1)$ worst-case time for lookups and $O(1)$ amortized expected time for insertions and deletions; it uses space proportional to the size of the set stored. Furthermore, lower bounds for the time complexity of a class of deterministic algorithms for the dictionary problem are proved. This class encompasses realistic hashing-based schemes that use linear space. Such algorithms have amortized worst-case time complexity $\Omega (\log n)$ for a sequence of n insertions and lookups; if the worst-case lookup time is restricted to $k$, then the lower bound becomes $\Omega (k \cdot n^{{1 / k}} )$.
ISSN:0097-5397
1095-7111
DOI:10.1137/s0097539791194094