Hash Table, also known as a hash map, is a data structure used to store data in an associative manner. It is a type of data structure that uses a hash function to map keys to values. The hash function produces an index, or a “hash code,” which is used to store or retrieve a corresponding value. In computer science, a hash table, or a hash map, is a data structure that maps keys to values for efficient lookup.
A hash table uses a hash function to generate an index from which the desired data can be quickly retrieved. The hash table consists of two main components, the hash function and the array of buckets or slots. The hash function takes the input key and generates an index to the array of buckets, and the array of buckets is where the values associated with the input key are stored. Each key is mapped to a bucket, which contains the associated value.
The hash function is used to determine where each element is going to be stored in the hash table. Generally, the hash function will have an input and yield an integer output, which serves as an index in the array of buckets. Depending on the type of data being stored, various types of hash functions can be used, in order to minimize collisions when storing multiple elements with the same key.
A hash table provides fast access to elements stored in it. Insertions and lookups take about constant time since they don’t depend on the number of elements stored, only on the size of the buckets array. Thus, hash tables are very efficient when it comes to lookups, insertions and deletions in terms of time complexity.
Hash tables are widely used in computer programming, database indexing, computer graphics, cryptography and many other fields. They have become extremely popular due to their efficient time complexity and the ability to store any type of data with minimal collisions. Hash tables are also used for implementing caches, memory management, database indexing, and many other applications.
