What are the different collision resolution techniques used in hashing?

In hashing, collision resolution techniques are used to handle situations where two or more keys are mapped to the same hash value. There are several collision resolution techniques commonly used in hashing, including:

1. Separate Chaining: In this technique, each hash table slot contains a linked list of elements that have the same hash value. When a collision occurs, the new element is simply appended to the linked list at the corresponding slot.

2. Open Addressing: In this technique, all elements 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, if a collision occurs, the algorithm checks the next slot in the table and continues until an empty slot is found. The linear probing technique suffers from clustering, where consecutive elements tend to cluster together, leading to poor performance.

4. Quadratic Probing: Quadratic probing addresses the clustering issue by using a quadratic function to determine the next slot to probe. The probing sequence follows a quadratic pattern, reducing the likelihood of clustering.

5. Double Hashing: Double hashing uses two hash functions to determine the next slot to probe. If a collision occurs, the algorithm applies the second hash function to calculate the step size for probing. This technique helps to distribute elements more evenly across the hash table.

6. Cuckoo Hashing: Cuckoo hashing is a technique that uses multiple hash functions and multiple hash tables. When a collision occurs, the algorithm tries to relocate the existing element to another hash table using one of the hash functions. This process continues until all elements are successfully placed or a maximum number of relocations is reached.

Each collision resolution technique has its advantages and disadvantages, and the choice of technique depends on factors such as the expected number of collisions, the size of the hash table, and the desired performance characteristics.