Hash Table Search Algorithm
A hash table is a data structure that is used to implement an associative array, which is a data structure that maps keys to values. A hash table search algorithm uses a hash function to map keys to indices in an array, allowing for constant-time lookups, inserts, and deletes.
The basic idea behind a hash table is to use a hash function to map keys to indices in an array. The hash function takes the key as input and returns an index, which is used to store the value associated with the key in the array. To look up a value, the hash function is applied to the key, giving the index of the value in the array. To insert a key-value pair, the hash function is applied to the key to determine the index at which the value should be stored, and the value is stored at that index. To delete a key-value pair, the value is simply removed from the array at the index determined by the hash function.
Hash table search algorithms are designed to be fast, with a time complexity of O(1) on average for lookups, inserts, and deletes. However, they can become slow if the hash function does not distribute keys evenly, causing many keys to map to the same index, resulting in collisions. To avoid collisions, hash table algorithms use collision resolution strategies such as chaining and open addressing. Chaining involves creating a linked list at each index, and inserting values into the appropriate linked list when collisions occur. Open addressing involves finding the next available index in the array when collisions occur.
Hash table algorithms are widely used in various applications, including database indexing, caching, and symbol tables in compilers.