A fusion tree is a type of tree data structure in computer science

Computer science

Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...

. It implements an associative array

Associative array

In computer science, an associative array is an abstract data type composed of a collection of pairs, such that each possible key appears at most once in the collection....

 with integer keys up to a fixed size; by exploiting the constant-time machine word multiplication operation available on many real processors, it is able to achieve all operations in


time (see Big O notation

Big O notation

In mathematics, big O notation is used to describe the limiting behavior of a function when the argument tends towards a particular value or infinity, usually in terms of simpler functions. It is a member of a larger family of notations that is called Landau notation, Bachmann-Landau notation, or...

), which is slightly faster asymptotically than a self-balancing binary search tree

Self-balancing binary search tree

In computer science, a self-balancing binary search tree is any node based binary search tree that automatically keeps its height small in the face of arbitrary item insertions and deletions....

.