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Next: Universal Hash Functions Up: CSE 2320: Algorithms and Previous: Multiplication Method

Universal Hashing

Any fixed hash function will have $\Theta(n)$ worst case time.

Choose hash function , independent of the keys to be stored.
Choice at prevents worst case behavior on multiple runs.

Suppose we want the hash function to uniformly distribute hash values over the hash table of size m.

Given h(x), we want P(h(x) = h(y)) = .

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