a Hashmap is a Map data structure. Like a list each item that is stored in a hashmap is stored at a particular index. This index is called a hash and it is generated using a hash function.
Hash functions accept the object to be stored as an argument and generate a number that is unique to it. different hashing functions have different trade-offs. a function that is too sparse will use up more space than required. while one that is not sparse enough will suffer from collisions where objects use the same hash.
External Links Edit
- Hashmap on Wikipedia