What is a hashmap and how is it implemented?

What is a hashmap and how is it implemented?

A hashmap is a data structure that stores key-value pairs for efficient data retrieval. It uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found.

Can you explain how the hash function works?

Sure! The hash function takes an input (the key) and produces a fixed-size string of bytes. The output is typically an integer that determines the index in the array where the value is stored.

What happens if two keys hash to the same index?

This is called a collision. Hashmaps handle collisions using methods like chaining (linking entries at the same index) or open addressing (finding another open slot).

Are there any performance considerations I should be aware of?

Yes, the performance of a hashmap can degrade if there are too many collisions or if the load factor (number of entries divided by the number of buckets) is too high. It's important to choose a good hash function and resize the hashmap when necessary.