Heap sort

Heap sort is an efficient sorting algorithm implemented with the heap data structure.

Algorithm

 * 1) Build a heap with the sorting array, using recursive insertion.
 * 2) Iterate to extract n times the maximum or minimum element in heap and heapify the heap.
 * 3) The extracted elements form a sorted subsequence.

Pseudocode
Heapsort(A as array) BuildHeap(A) for i = n to 1 swap(A[1], A[i]) n = n - 1 Heapify(A, 1)

BuildHeap(A as array) n = elements_in(A) for i = floor(n/2) to 1 Heapify(A,i)

Heapify(A as array, i as int) left = 2i right = 2i+1

if (left <= n) and (A[left] > A[i]) max = left else max = i

if (right<=n) and (A(right] > A[max])       max = right

if (max != i)       swap(A[i], A[max]) Heapify(A, max)

Implementations

 * C in-place non-recursive