排序算法——快速排序

#include<stdio.h>	

/*将数组a[low...high]按照枢轴分成两部分，在枢轴之前的不大于它，在枢轴之后的不小于它
并且返回枢轴的最终位置*/
int Partition(int a[], int low, int high)
{
	int pivotkey = a[low];
	while (low < high)
	{
		while (low < high&&a[high] >= pivotkey)  --high;
		a[low] = a[high];
		while (low < high&&a[low] <= pivotkey)  ++low;
		a[high] = a[low];
	}
	a[low] = pivotkey;
	return low;
}

/*快速排序*/
void QuickSort(int a[], int low, int high)
{
	int pivotloc;   //枢轴的位置
	if (low < high)
	{
		pivotloc = Partition(a, low, high);
		QuickSort(a, low, pivotloc - 1);
		QuickSort(a, pivotloc + 1, high);
	}
}

int main()
{
	int a[8] = { 1, 2, 4, 5, 3, 9, 7, 8 };

	QuickSort(a,0,7);
	//merge(a, 0, 3, 7);
	for (int i = 0; i < 8; i++)
	{
		printf("%d  ", a[i]);
	}
	return 0;
}