快速排序的算法實現

void exch(int *p,int *q)  //Data Exchange
{
    int temp;
    temp = *p;
    *p = *q;
    *q = temp;
}

int partition(int *a,int left,int right)    //Data Partition
{
    int i = left-1;
    int j = right;
    int tag = a[right];

    while(1)
    {
        while(tag >= a[++i])
            ;
        while(tag <= a[--j])
            if(j == left)
                break;
        if(i >= j)
            break;
        exch(&a[i],&a[j]);
    }
    exch(&a[i],&a[right]);
    return i;
}

void quick_sort(int *a,int left,int right)
{
    if(right <= left) return;
    int pos = partition(a,left,right);
    quick_sort(a,left,pos-1);
    quick_sort(a,pos+1,right);
}