Van Emde Boas Tree

A Van Emde Boas tree (or Van Emde Boas priority queue), also known as a vEB tree, is a tree data structure which implements an associative array with m-bit integer keys. It performs all operations in O(log m) time. Notice that m is the size of the keys — therefore O(log m) is O(log log n) in a tree where every key below n is set, exponentially better than a full self-balancing binary search tree. They also have good space efficiency when they contain a large number of elements, as discussed below. They were invented by a team led by Peter van Emde Boas in 1975.