数据结构中双向链表和双向循环链表C语言实现

#include <stdio.h>
#include <stdlib.h>
#define FLAG -1 //停止输入的标志

typedef struct Node
{
    struct Node * prior;
    int data;
    struct Node * next;
}LNode,*LinkList;

void CreateDoubleLinkedList(LinkList L);
void CreateDoubleCircularLinkedList(LinkList L);
void ShowDoubleLinkedList(LinkList L);
void InsertDoubleLinkedList(LinkList L,int num,int local);//local是插入的位置
void DeleteDoubleLinkedList(LinkList L,int local);//local是删除的位置
LinkList GetLinkList(LinkList L,int local);
void CreateDoubleCircularLinkedList(L);
void ShowDoubleCircularLinkedList(LinkList L);
void InsertDoubleCircularLinkedList(LinkList L,int num,int local);
void DeleteDoubleCircularLinkedList(LinkList L,int local);

void main()
{
    LinkList L = (LinkList)malloc(sizeof(LNode));

    /*printf("创建双向链表：\n");
    CreateDoubleLinkedList(L);
    printf("遍历双向链表：\n");
    ShowDoubleLinkedList(L);
    InsertDoubleLinkedList(L,100,3);
    printf("插入元素后的双向链表：\n");
    ShowDoubleLinkedList(L);
    printf("删除元素后的双向链表：\n");
    DeleteDoubleLinkedList(L,3);
    ShowDoubleLinkedList(L);*/
    printf("创建双向循环链表：\n");
    CreateDoubleCircularLinkedList(L);
    printf("遍历双向链表：\n");
    ShowDoubleCircularLinkedList(L);
    printf("插入元素后的链表：\n");
    InsertDoubleCircularLinkedList(L,100,3);
    ShowDoubleCircularLinkedList(L);
    printf("删除元素后的链表：\n");
    DeleteDoubleCircularLinkedList(L,3);
    ShowDoubleCircularLinkedList(L);
}

void CreateDoubleLinkedList(LinkList L)//尾插法创建双向链表
{
    LinkList r,s;//s用于生成新的结点
    int x = 0;
    r = L;
    scanf("%d",&x);
    while(x != FLAG)//尾插法
    {
        s = (LinkList)malloc(sizeof(LNode));
        s->data = x;
        r->next = s;
        s->prior = r;
        r = r->next;
        scanf("%d",&x);
    }
    r->next = NULL;
}

void ShowDoubleLinkedList(LinkList L)//遍历停止的标志是什么  游标e->next != L;
{
    /*LinkList e = L->next;
    printf("%d",e->data);
    while(e)
    {
        e = e->next;
        printf("->%d",e->data);
    }
    printf("\n");*/
    LinkList p = L->next;
    printf("%d",p->data);
    p = p ->next;
    while(p != NULL)//先输出再后移
    {
        printf("->%d",p->data);
        p = p->next;
    }
    printf("\n");

}

void InsertDoubleLinkedList(LinkList L,int num,int local)
{
    LinkList p;
    int i;//i是插入的下标
    i = local - 1;
    p = GetLinkList(L,local - 1);
    if(p == NULL) //假设链表的长度是2   插入位置是3  没问题  但是插入位置如果是4及以上 就会出现p == NULL的情况
    {
        printf("插入位置不合法！\n");
        exit(1);
    }
    /*else if(p->next == NULL) // 说明此时是在最后插入元素
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        //p->next->prior = s;
        p->next = s;
        s->prior = p;
    }
    else
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        p->next->prior = s;   //NULL->prior = s 的情况是什么意思
        p->next = s;
        s->prior = p;
    }*/
    //简化写法
    else
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        if(p->next)p->next->prior = s;  // 存在后继结点的情况
        p->next = s;
        s->prior = p;
    }

}

void DeleteDoubleLinkedList(LinkList L,int local)
{
    LinkList p,q;
    p = GetLinkList(L,local - 1);

    if(p == NULL)
    {
        printf("删除位置不合法！");
        exit(1);
    }
    else
    {
        if(p->next == NULL)
        {
            printf("删除位置不合法！");
            exit(1);
        }
        else
        {
            q = p->next;
            p->next = q->next;
            if(q->next)//为NULL说明删除的是最后一个结点 不是NULL说明不是最后一个结点
                q->next->prior = p;
            free(q);

        }
    }
}

LinkList GetLinkList(LinkList L,int local)
{
    LinkList p = L;
    int j = 0;//计数器
    while(p != NULL && j < local)
    {
        p = p->next;
        j++;
    }
    return p;
}

//双向循环链表
void CreateDoubleCircularLinkedList(LinkList L)//尾插法创建循环双向链表
{
    LinkList r,s;//s用于生成新的结点
    int x = 0;
    r = L;
    scanf("%d",&x);
    while(x != FLAG)//尾插法
    {
        s = (LinkList)malloc(sizeof(LNode));
        s->data = x;
        r->next = s;
        s->prior = r;
        r = r->next;
        scanf("%d",&x);
    }
    //不同点在于首尾相连
    r->next = L;
    L->prior = r;
}

void ShowDoubleCircularLinkedList(LinkList L)
{
    LinkList p = L->next;
    printf("%d",p->data);
    p = p->next;
    while(p != L)
    {
        printf("->%d",p->data);
        p = p->next;
    }
    printf("\n");
}

void InsertDoubleCircularLinkedList(LinkList L,int num,int local)
{
    LinkList p;
    int i;//i是插入的下标
    i = local - 1;
    p = GetLinkList(L,local - 1);
    if(p == L) //假设链表的长度是2   插入位置是3  没问题  但是插入位置如果是4及以上 就会出现p == NULL的情况
    {
        printf("插入位置不合法！\n");
        exit(1);
    }
    /*else if(p->next == NULL) // 说明此时是在最后插入元素
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        //p->next->prior = s;
        p->next = s;
        s->prior = p;
    }
    else
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        p->next->prior = s;   //NULL->prior = s 的情况是什么意思
        p->next = s;
        s->prior = p;
    }*/
    //简化写法
    else
    {
        LinkList s = (LinkList)malloc(sizeof(LNode));
        s->data = num;
        s->next = p->next;
        //if(p->next)p->next->prior = s; 不需要判断这一步  因为双向循环链表一定是存在后继的 纵使在最后一个插入 他的后继是第一个元素
        p->next = s;
        s->prior = p;
    }

}

void DeleteDoubleCircularLinkedList(LinkList L,int local)
{
    LinkList p,q;
    p = GetLinkList(L,local - 1);

    if(p == L)
    {
        printf("删除位置不合法！");
        exit(1);
    }
    else
    {
        if(p->next == L)//不同点
        {
            printf("删除位置不合法！");
            exit(1);
        }
        else
        {
            q = p->next;
            p->next = q->next;
            /*if(q->next)//为NULL说明删除的是最后一个结点 不是NULL说明不是最后一个结点
                q->next->prior = p;*/
            free(q);

        }
    }
}