QUICK SORT

int partition(int A[] , int len)
{
        int pivot = A[0];

        int low = 0;
        int high = len-1;
        while(low < high){
                for(; high>low && A[high] >= pivot; high--);
                        A[low] = A[high];
                for(; high>low && A[low] <= pivot; low++);
                        A[high] = A[low];

        }

        A[low] = pivot;

        return low;
}

void quicksort(int A[], int len)
{
        if(len == 0 || len == 1)
                return;

        int index = partition(A,len);

        quicksort(A, index);
        quicksort(A+index+1, len-index-1);
}
int main()
{
        int A[] = {1,5,4,7,9,2,3,6,8};

        int len = sizeof(A)/sizeof(A[0]);

        for(int i = 0; i < len ; i++)
                printf("%d ", A[i]);

        printf("\n");
        quicksort(A,len);
        for(int i = 0; i < len ; i++)
                printf("%d ", A[i]);

        printf("\n");
        return 1;
}