NIST

perfect hashing

(algorithm)

Definition: A hash function that maps each different key to a distinct integer. Usually all possible keys must be known beforehand. A hash table that uses a perfect hash has no collisions.

Formal Definition: A function f is perfect for a set of keys K iff ∀ j, k ∈ K f(j) = f(k) → j = k.

Also known as optimal hashing.

Specialization (... is a kind of me.)
minimal perfect hashing, order-preserving minimal perfect hashing.

See also Pearson's hash.

Note: After BJ.

Author: PEB

Implementation

See the implementations at minimal perfect hashing and Gonnet and Baeza-Yates's insert (C), search (C) implementations.

More information

Martin Dietzfelbinger, Anna Karlin, Kurt Melhorn, Friedhelm Meyer Auf Der Heide, Hans Rohnert, and Robert E. Tarjan, Dynamic Perfect Hashing: Upper and Lower Bounds, SIAM J. Comput., 23(4):738-761, August 1994.


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Entry modified 12 February 2019.
HTML page formatted Wed Mar 13 12:42:46 2019.

Cite this as:
Paul E. Black, "perfect hashing", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 12 February 2019. (accessed TODAY) Available from: https://www.nist.gov/dads/HTML/perfecthash.html