HashTable

Hashing

Hashing is used to map data of an arbitrary size to data of a fixed size. The values returned by a hash function are called hash values, hash codes, or simply hashes. If two keys map to the same value, a collision occurs
Hash Map: a hash map is a structure that can map keys to values. A hash map uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found.
Collision Resolution
Separate Chaining: in separate chaining, each bucket is independent, and contains a list of entries for each index. The time for hash map operations is the time to find the bucket (constant time), plus the time to iterate through the list
Open Addressing: in open addressing, when a new entry is inserted, the buckets are examined, starting with the hashed-to-slot and proceeding in some sequence, until an unoccupied slot is found. The name open addressing refers to the fact that the location of an item is not always determined by its hash value