Searching Algorithms Questions Medium
There are several collision resolution techniques used in hash tables to handle situations where two or more keys are mapped to the same hash value. Some of the commonly used techniques are:
1. Separate Chaining: In this technique, each bucket in the hash table is implemented as a linked list. When a collision occurs, the collided keys are stored in the same bucket as a linked list. This allows multiple keys to be stored at the same index.
2. Open Addressing: In this technique, all the keys are stored directly in the hash table itself. When a collision occurs, the algorithm probes for the next available slot in the table until an empty slot is found. There are different methods for probing, such as linear probing, quadratic probing, and double hashing.
3. Linear Probing: In linear probing, when a collision occurs, the algorithm checks the next slot in the table and continues to probe sequentially until an empty slot is found. The main disadvantage of linear probing is the clustering effect, where consecutive slots tend to be filled, leading to poor performance.
4. Quadratic Probing: Quadratic probing uses a quadratic function to probe for the next available slot. It reduces the clustering effect by probing at positions that are further apart. However, it can still suffer from clustering if the table is heavily loaded.
5. Double Hashing: Double hashing uses a secondary hash function to determine the next probe position. It provides a more uniform distribution of keys and reduces clustering. The secondary hash function is typically computed as a function of the original hash value.
These collision resolution techniques ensure that all keys are stored and retrieved correctly in a hash table, even when collisions occur. The choice of technique depends on factors such as the expected number of collisions, the load factor of the table, and the desired performance characteristics.