hajautustaululla

Hajautustaululla, often translated as hash table or hash map, is a data structure that implements an associative array abstract data type. It uses a hash function to compute an index, also known as a hash code, into an array of buckets or slots. The key-value pairs are then stored in these buckets. The primary goal of a hash table is to provide efficient insertion, deletion, and lookup operations, ideally in constant average time, O(1).

When an element is to be inserted, its key is passed to the hash function, which generates an index. This index points to a bucket within the hash table. If the bucket is empty, the element is placed there. If the bucket is already occupied, a collision occurs. Various collision resolution strategies exist, such as separate chaining (where each bucket holds a linked list of elements) or open addressing (where the algorithm probes for an alternative slot in the table).

The effectiveness of a hash table heavily relies on the quality of its hash function. A good hash function distributes keys uniformly across the buckets, minimizing collisions. The load factor, which is the ratio of the number of elements to the number of buckets, also influences performance. A high load factor can lead to more collisions and slower operations. Hash tables are widely used in computer science for various applications, including symbol tables in compilers, database indexing, and caching mechanisms.