What are hash functions and how are they used in data structures?

What are hash functions and how are they used in data structures?

Hash functions are algorithms that map data of arbitrary size to fixed-size values. They are commonly used in data structures like hash tables to enable fast data retrieval.

Can you explain how a hash table works?

Sure! A hash table uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found. This allows for average-case constant time complexity for lookups.

What happens if two inputs produce the same hash value?

This is known as a collision. Hash tables handle collisions using methods like chaining (linking entries) or open addressing (finding another slot).

Are there any downsides to using hash functions?

Yes, hash functions can lead to collisions, and if not handled properly, they can degrade performance. Additionally, choosing a poor hash function can lead to uneven distribution of data.

Can you give me an example of a good hash function?

A commonly used hash function is SHA-256, which produces a 256-bit hash value and is widely used in security applications.