Heap Sort

Heap sort is a comparison based sorting algorithm. It is similar to selection sort where we first find the maximum element and place the maximum element at the end. We repeat the same process for remaining element.

									void MaxHeapify(int* data, int heapSize, int index) {
	int left = (index + 1) * 2 - 1;
	int right = (index + 1) * 2;
	int largest = 0;

	if (left < heapSize && data[left] > data[index])
		largest = left;
	else
		largest = index;

	if (right < heapSize && data[right] > data[largest])
		largest = right;

	if (largest != index)
	{
		int temp = data[index];
		data[index] = data[largest];
		data[largest] = temp;

		MaxHeapify(data, heapSize, largest);
	}
}

void HeapSort(int* data, int count) {
	int heapSize = count;

	for (int p = (heapSize - 1) / 2; p >= 0; --p)
		MaxHeapify(data, heapSize, p);

	for (int i = count - 1; i > 0; --i)
	{
		int temp = data[i];
		data[i] = data[0];
		data[0] = temp;

		--heapSize;
		MaxHeapify(data, heapSize, 0);
	}
}

Example

									int data[] = { -1, 25, -58964, 8547, -119, 0, 78596 };
HeapSort(data, 7);

Output