Hashing Questions Long
Open addressing and closed addressing are two different techniques used in hashing to handle collisions.
Open addressing, also known as closed hashing, is a method where all the elements are stored directly in the hash table itself. When a collision occurs, i.e., when two elements are mapped to the same hash index, the algorithm searches for the next available slot in the table and inserts the element there. This process continues until an empty slot is found. The main advantage of open addressing is that it minimizes the memory overhead since no additional data structures are required. However, it can lead to clustering, where consecutive elements are placed together, causing longer search times.
On the other hand, closed addressing, also known as open hashing, is a technique where each slot in the hash table contains a linked list or some other data structure to store multiple elements that hash to the same index. When a collision occurs, the element is inserted into the linked list at the corresponding index. Closed addressing ensures that all elements are stored within the hash table, even if collisions occur. It provides better performance in terms of search time since elements with the same hash index are stored together. However, it requires additional memory to store the linked lists or other data structures.
In summary, the main difference between open addressing and closed addressing lies in how collisions are handled. Open addressing directly stores elements in the hash table itself, searching for the next available slot when a collision occurs. Closed addressing, on the other hand, uses linked lists or other data structures to store multiple elements at the same hash index. Open addressing minimizes memory overhead but can lead to clustering, while closed addressing ensures all elements are stored but requires additional memory.