八大排序之堆排序

#pragma once

void AdjustDown(int*a,size_t size, size_t parent)
{
	size_t child = parent * 2 + 1;
	while (child < size)
	{
		if (child + 1 < size&&a[child + 1] > a[child])
		{
			child++;
		}
		if (a[child]>a[parent])
		{
			swap(a[child], a[parent]);
			parent = child;
			child = parent * 2 + 1;
		}
		else
		{
			break;
		}
	}
}
void HeapSort(int *a,size_t size)
{
	for (size_t i = (size - 2) / 2; i >= 0; i--)
	{
		AdjustDown(a,size,i);
	}
	for (size_t i = 0; i < size; i++)
	{
		swap(a[0], a[size - 1 - i]);
		AdjustDown(a, size - 1 - i, 0);
	}
}