hashtaulukoiden

Hashtaulukot, also known as hash tables or hash maps, are data structures that implement an associative array abstract data type. They provide efficient key-value storage and retrieval. The core idea behind a hash table is to use a hash function to compute an index, or "hash code," into an array of buckets or slots. Ideally, the hash function distributes keys uniformly across these buckets.

When an element is inserted, its key is passed through the hash function, which generates an index. The element is then stored at that index in the array. To retrieve an element, the same hash function is applied to the key, and the element is looked up at the calculated index.

However, hash collisions can occur when two different keys hash to the same index. Various collision resolution strategies exist, such as separate chaining (where each bucket holds a linked list of elements that hash to it) or open addressing (where the algorithm probes for the next available slot in the array). The choice of hash function and collision resolution method significantly impacts the performance of a hash table. On average, hash tables offer constant time complexity, O(1), for insertion, deletion, and search operations, making them a fundamental tool in computer science for various applications, including dictionaries, symbol tables, and caching.