What is the difference between linear probing and quadratic probing in hashing?

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What is the difference between linear probing and quadratic probing in hashing?

Linear probing and quadratic probing are two different techniques used in open addressing for resolving collisions in hashing.

Linear probing is a simple method where if a collision occurs, the next available slot in the hash table is checked sequentially until an empty slot is found. The probing sequence is linear, meaning it increments by a fixed amount (usually 1) for each collision. This can lead to clustering, where consecutive elements are placed close together, resulting in poor performance.

On the other hand, quadratic probing uses a quadratic function to determine the next probing position. If a collision occurs, the probing sequence is determined by incrementing the position by a quadratic function of the number of collisions. The function can be something like f(i) = i^2, where i is the number of collisions. This helps to distribute the elements more evenly in the hash table, reducing clustering and improving performance.

In summary, the main difference between linear probing and quadratic probing is the way they determine the next probing position. Linear probing uses a fixed increment, while quadratic probing uses a quadratic function. Quadratic probing tends to provide better performance by reducing clustering.