/*链表存储结构的定义*/
typedef struct CLinkList
{
    int data;
    struct CLinkList *next;
}node;

/*初始化循环链表*/
void ds_init(node **pNode)
{
    int item;
    node *temp;
    node *target;

    printf("输入结点的值，输入0完成初始化\n");

    while(1)
    {
        scanf("%d", &item);
        fflush(stdin);

        if(item == 0)
            return;

        if((*pNode) == NULL)
        { /*循环链表中只有一个结点*/
            *pNode = (node*)malloc(sizeof(struct CLinkList));
            if(!(*pNode))
                exit(0);
            (*pNode)->data = item;
            (*pNode)->next = *pNode;
        }
        else
        {
            /*找到next指向第一个结点的结点*/
            for(target = (*pNode); target->next != (*pNode); target = target->next)
              ;

            /*生成一个新的结点*/
            temp = (node *)malloc(sizeof(struct CLinkList));

            if(!temp)
                exit(0);

            temp->data = item;
            temp->next = *pNode;
            target->next = temp;
        }
    }
}

/*插入结点*/
/*参数：链表的第一个结点，插入的位置*/
void ds_insert(node **pNode , int i)
{
    node *temp;
    node *target;
    node *p;
    int item;
    int j = 1;

    printf("输入要插入结点的值:");
    scanf("%d", &item);

    if(i == 1)
    { //新插入的结点作为第一个结点
        temp = (node *)malloc(sizeof(struct CLinkList));

        if(!temp)
            exit(0);

        temp ->data = item;

        /*寻找到最后一个结点*/
        for(target = (*pNode); target->next != (*pNode); target = target->next)
            ;

        temp->next = (*pNode);
        target->next = temp;
        *pNode = temp;
    }
    else
    {
        target = *pNode;

        for( ; j < (i-1); ++j )
        {
            target=target->next;
        }

        temp = (node *)malloc(sizeof(struct CLinkList));

        if(!temp)
            exit(0);

        temp ->data = item;
        p = target->next;
        target->next = temp;
        temp->next = p;
    }
}

/*删除结点*/
void ds_delete(node **pNode, int i)
{
    node *target;
    node *temp;
    int j = 1;

    if(i == 1)
    { //删除的是第一个结点
        /*找到最后一个结点*/
        for(target = *pNode; target->next != *pNode;target = target->next)
            ;

        temp = *pNode;
        *pNode = (*pNode)->next;
        target->next = *pNode;
        free(temp);
    }
    else
    {
        target = *pNode;

        for( ; j < i-1; ++j )
        {
            target = target->next;
        }

        temp = target->next;
        target->next = temp->next;
        free(temp);
    }
}

/*返回结点所在位置*/
int ds_search(node *pNode, int elem)
{
    node *target;
    int i = 1;

    for(target = pNode; target->data != elem && target->next != pNode; ++i)
    {
        target = target->next;
    }

    if(target->next == pNode) /*表中不存在该元素*/
        return 0;
    else
        return i;
}

/*遍历*/
void ds_traverse(node *pNode)
{
    node *temp;
    temp = pNode;
    printf("***********链表中的元素******************\n");

    do
    {
        printf("%4d ", temp->data);
    }while((temp = temp->next) != pNode);

    printf("\n");
}