void quicksort(int array[], int left, int right, int len)
{
    int key_left = left;
    int key_right = right;
    int pivot = array[left];
    int i, j;

    ++count;
    //printf("퀵소트 %d번째 : ", count);

    while (left < right)
    {
        while (array[left] < pivot)
            left++;

        while (array[right] > pivot)
            right--;

        if (left < right)
            swap(&array[left], &array[right]);
        else
            swap(&array[right], &pivot);
    }
    /*
    for (i = 0; i < len; i++)
        printf("%d ", array[i]);
    printf("\n");
    */
    pivot = right;
    left = key_left;
    right = key_right;

    if (left < pivot - 1)
        quicksort(array, left, pivot - 1, len);
    if (right > pivot + 1)
        quicksort(array, pivot + 1, right, len);
}