(redirected from at the top of the heap)
Also found in: Dictionary, Thesaurus, Legal, Idioms.


An area of memory used for dynamic memory allocation where blocks of memory are allocated and freed in an arbitrary order and the pattern of allocation and size of blocks is not known until run time. Typically, a program has one heap which it may use for several different purposes.

Heap is required by languages in which functions can return arbitrary data structures or functions with free variables (see closure). In C functions malloc and free provide access to the heap.

Contrast stack. See also dangling pointer.


A data structure with its elements partially ordered (sorted) such that finding either the minimum or the maximum (but not both) of the elements is computationally inexpensive (independent of the number of elements), while both adding a new item and finding each subsequent smallest/largest element can be done in O(log n) time, where n is the number of elements.

Formally, a heap is a binary tree with a key in each node, such that all the leaves of the tree are on two adjacent levels; all leaves on the lowest level occur to the left and all levels, except possibly the lowest, are filled; and the key in the root is at least as large as the keys in its children (if any), and the left and right subtrees (if they exist) are again heaps.

Note that the last condition assumes that the goal is finding the minimum quickly.

Heaps are often implemented as one-dimensional arrays. Still assuming that the goal is finding the minimum quickly the invariant is

heap[i] <= heap[2*i] and heap[i] <= heap[2*i+1] for all i,

where heap[i] denotes the i-th element, heap[1] being the first. Heaps can be used to implement priority queues or in sort algorithms.


In programming, it refers to a common pool of memory that is available to the program. The management of the heap is either done by the applications themselves, allocating and deallocating memory as required, or by the operating system or other system program.
References in periodicals archive ?
In less than three years, Friedman has both broadened and deepened the company's revenue streams, put customers at the top of the heap and created an employee culture where success is a given.
The American has dominated the Open era like no other and just one more Major win will place him at the top of the heap with a record-breaking lucky 13 victories.
With 300-400 MHz models now at the top of the heap, prices for computers in the 200 MHz realm will undoubtedly offer a good bargain.
The commitment of Washington's 400-plus growers sends them to their peach trees five to seven times per season, part of a special "tree ripe, tree conditioned" program that puts their fruit at the top of the heap.
LOVE him or loathe him, there was something quite evident in the form of Mick Hucknall, the mainstay of Simply Red and a star who's graced the charts for nigh on 30 years, and that was the immense power of a voice that's lost nothing in its range or clarity in all his time at the top of the heap.
However, from the standpoint of that mysterious principle of evolution that has seen life on Earth transformed step by step from a single-cell like an amoeba right up through members of the animal kingdom to man at the top of the heap, perhaps it does make a kind of sense.
1 Italian in the Valley, Panzanella appears to be doing well enough to continue as its replacement at the top of the heap.