# quadratic probing

(algorithm)

**Definition:**
A method of *open addressing* for a *hash table* in which a *collision* is resolved by putting the item in the next empty place given by a *probe sequence*. The space between places in the sequence increases quadratically.

**See also**
*double hashing*, *linear probing*.

*Note:
Deletion may be hard because finding collisions again relies on not creating empty spots. One solution is to mark an entry as deleted so it can be reused for insertion, but the search list is intact. *

Author: PEB

## Implementation

insert (C and Pascal)
## More information

An explanation of how quadratic equations got their name.

Go to the
Dictionary of Algorithms and Data
Structures home page.

If you have suggestions, corrections, or comments, please get in touch
with Paul Black.

Entry modified 12 February 2019.

HTML page formatted Wed Mar 13 12:42:46 2019.

Cite this as:

Paul E. Black, "quadratic probing", in
*Dictionary of Algorithms and Data Structures* [online], Paul E. Black, ed. 12 February 2019. (accessed TODAY)
Available from: https://www.nist.gov/dads/HTML/quadraticprb.html