C_数据结构_快速排序

# include <stdio.h>

void QuickSort(int * a, int low, int high);
int FindPos(int * a, int low, int high);

int main(void)
{
    int a[6] = {2, 1, 0, 5, 8, 3};
    int i;

    QuickSort(a, 0, 5); //第二个参数表示第一个元素的下标，第三个参数表示最后一个元素的下标，表示把a[0]-a[5]进行排序

    for (i=0; i<6; ++i)
        printf("%d ", a[i]);
    printf("
");

    return 0;
}

void QuickSort(int * a, int low, int high)
{
    int pos;

    if (low < high)
    {
        pos = FindPos(a, low, high);
        QuickSort(a, low, pos-1);
        QuickSort(a, pos+1, high);
    }
}

int FindPos(int * a, int low, int high)
{
    int val = a[low];

    while (low < high)
    {
        while (low < high && a[high]>=val)
            --high;
        a[low] = a[high];

        while (low<high && a[low]<=val)
            ++low;
         a[high] = a[low];
    } //终止while循环后low和high一定是相等的
    a[low] = val;

    return low; //high可以改为low，但不能改为val，也不能改为a[low]和a[high]
}