What is the difference between a linear probing and a quadratic probing in hash tables?

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What is the difference between a linear probing and a quadratic probing in hash tables?

Linear probing and quadratic probing are two different techniques used in resolving collisions in hash tables.

Linear probing is a collision resolution method where, if a collision occurs, the next available slot in the hash table is searched sequentially until an empty slot is found. In linear probing, the interval between successive probes is fixed and typically one. This means that if the initial hash index is occupied, the next index to be probed will be the next consecutive index.

On the other hand, quadratic probing is a collision resolution method where the interval between successive probes is determined by a quadratic function. Instead of searching sequentially, quadratic probing uses a quadratic equation to calculate the next index to be probed. The equation typically takes the form of (hashIndex + i^2) % tableSize, where i is the number of collisions encountered. This means that if the initial hash index is occupied, the next index to be probed will be determined by adding the square of the collision count to the initial hash index.

The main difference between linear probing and quadratic probing lies in the way they handle collisions. Linear probing has a fixed interval between probes, which can lead to clustering and a higher chance of further collisions. Quadratic probing, on the other hand, uses a quadratic equation to determine the next probe index, which helps to distribute the elements more evenly and reduce clustering.

In summary, linear probing uses a fixed interval between probes, while quadratic probing uses a quadratic equation to determine the next probe index. Quadratic probing tends to distribute elements more evenly and reduce clustering compared to linear probing.