What is a Hash Function? What makes a good hash function?

Difficulty: 5/10

collision resistance, uniform distribution, performance

Hash Function

A hash function deterministically converts a key into a hash value, which is then used to select a bucket or slot in a Hash Table. A good non-cryptographic hash function should distribute common input keys uniformly, be fast to compute, and minimize systematic collisions.

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Deterministic: the same key must produce the same hash during the relevant lifetime.
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Good distribution: keys should spread across buckets rather than cluster.
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Fast computation: hashing occurs frequently in lookup and insertion paths.
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Low collision tendency for the expected key distribution.
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A hash function should work well with the table's bucket-index calculation.
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Cryptographic hashes optimize for security properties and are usually much more expensive than ordinary Hash Table hashes.

Scenario Questions

0-2 years experience

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