Searching Algorithms Questions Medium
Double hashing is a collision resolution technique used in searching algorithms, particularly in hash tables. It involves using two different hash functions to determine the index of a key in the hash table.
In double hashing, when a collision occurs (i.e., two keys are mapped to the same index), a second hash function is applied to calculate an offset value. This offset value is then added to the original index to find an alternative index for the key.
The second hash function is typically chosen to be independent of the first hash function to minimize the chances of generating the same offset for different keys. This helps distribute the keys more evenly across the hash table, reducing the likelihood of collisions.
To search for a key using double hashing, the first hash function is applied to calculate the initial index. If the key is not found at that index, the second hash function is used to calculate the offset, which is added to the initial index. This process is repeated until either the key is found or an empty slot is encountered.
Double hashing provides a more efficient collision resolution method compared to linear probing or quadratic probing, as it reduces the clustering effect that can occur with these techniques. It helps maintain a more uniform distribution of keys in the hash table, resulting in better search performance.