编码实现环状单向链表（尾指针直接指向头指针，中间没有空节点），去除连续的重复元素的操作。

#include <stdio.h>
#include <stdlib.h>

#define PERR    printf("FILE: %s, FUNCTION: %s, LINE: %d
",
                                    __FILE__, __func__, __LINE__)

struct Tnode
{
    struct Tnode *next;
    int value;
};

void Del_Repeat_Node(struct Tnode **head)
{
    if(NULL == head || NULL == *head){
        return;
    }

    struct Tnode *pnode = *head, *fnode = NULL;
    
    while(pnode ->next != *head)
    {
        if(pnode->next->value == pnode->value)
        {
            fnode = pnode->next;
            pnode->next = fnode->next;
            free(fnode);
            continue;
        }
        pnode = pnode->next;
    }
    if((*head)->next == *head)//当(或删除后只有)只有一个节点
        return ;
    if(pnode->value == (*head)->value)//当尾结点的value也等于头结点的value
    {
        fnode = *head;
        pnode->next = fnode->next;
        *head = pnode;
        free(fnode);
    }
}

//以下为测试代码
//插入结点到表头
int Insert_to_head(struct Tnode **head, int value)
{
    struct Tnode *new_node = 
            (struct Tnode *)calloc(1, sizeof(struct Tnode));
    if(NULL == new_node){
        perror("malloc");
        return -1;
    }
    //填充结点信息
    new_node->value = value;
    new_node->next = NULL;

    if(*head == NULL)
    {
        *head = new_node;
        (*head)->next  = *head;
    }
    else
    {
        struct Tnode *tail = *head;
        while(tail->next != *head)
            tail = tail->next;

        new_node->next = *head;
        tail->next = new_node;
        *head = new_node;
    }
    return 0;
}

//遍历链表
int traverse_link(struct Tnode *head)
{
    if(NULL == head)
        return -1;
    struct Tnode *pnode = head;
    while(pnode->next != head)
    {
        printf("%d	", pnode->value);
        pnode = pnode->next;
    }

    printf("%d
", pnode->value);

    return 0;
}


int main()
{
    int i;
    struct Tnode *head = NULL;

    Insert_to_head(&head, 1);

    Insert_to_head(&head, 1);
    

    Insert_to_head(&head, 1);
    Insert_to_head(&head, 2);
    Insert_to_head(&head, 2);
    
    Insert_to_head(&head, 1);

    traverse_link(head);

    Del_Repeat_Node(&head);

    traverse_link(head);

    return 0;
}