双向循环链表

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基本结构

typedef int ElemType;typedef int DataType;typedef struct DNode{    ElemType data;    struct DNode *pre, *next;}DNode, *DLinkList;

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函数

• 创建双向循环链表

void ListCreate(DLinkList L, int n){    int i;    DLinkList p, s;    p = L;    L->pre = L->next = L;                           //表为空时，前驱和后继都指向自己    for(i = 0; i < n; i ++)    {        s = (DLinkList)malloc(sizeof(DNode));        scanf("%d", &s->data);        p->next = s;                                //前驱和后继相互连接        s->pre = p;        s->next = L;                             //头和尾互指        L->pre = s;        p = s;    }}

• 插入结点

void ListInsert(DLinkList L, int i , ElemType e)//在第i个位置插入元素e{    DLinkList s, p = L;    while(p->next != L && i > 1)                       //寻找第i-1个结点    {        p = p->next;        i--;    }    s = (DLinkList)malloc(sizeof(DNode));    s->data = e;    s->next = p->next;    //if(p->next != NULL)                           //非循环链表需要判断是否为最后一个结点        p->next->pre = s;    s->pre = p;    p->next = s;}

• 删除结点

void ListDelete(DLinkList L, int i, ElemType *e)//删除第i个结点， 并由*e返回其值{    DLinkList p = NULL, q = L;    while(q->next != L && i >= 1)                  //直到第i个结点    {        p = q;                                  //p为q的前驱        q = q->next;        i--;    }    p->next = q->next;    //if(q->next != NULL)                         //非循环链表需要判断是否为最后一个结点        q->next->pre = p;    *e = q->data;    free(q);}

• 正序遍历

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

• 逆序遍历

void ListReTraverse(DLinkList L){    DLinkList p = L;    while(p->pre != L)    {        p = p->pre;        printf("%d", p->data);    }    printf("\n");}

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测试代码

#include <stdio.h>#include <stdlib.h>typedef int ElemType;typedef int DataType;typedef struct DNode{    ElemType data;    struct DNode *pre, *next;}DNode, *DLinkList;void ListCreate(DLinkList L, int n){    int i;    DLinkList p, s;    p = L;    L->pre = L->next = L;                           //表为空时，前驱和后继都指向自己    for(i = 0; i < n; i ++)    {        s = (DLinkList)malloc(sizeof(DNode));        scanf("%d", &s->data);        p->next = s;                                //前驱和后继相互连接        s->pre = p;        s->next = L;                             //头和尾互指        L->pre = s;        p = s;    }}void ListInsert(DLinkList L, int i , ElemType e)//在第i个位置插入元素e{    DLinkList s, p = L;    while(p->next != L && i > 1)                       //寻找第i-1个结点    {        p = p->next;        i--;    }    s = (DLinkList)malloc(sizeof(DNode));    s->data = e;    s->next = p->next;    //if(p->next != NULL)                           //非循环链表需要判断是否为最后一个结点        p->next->pre = s;    s->pre = p;    p->next = s;}void ListDelete(DLinkList L, int i, ElemType *e)//删除第i个结点， 并由*e返回其值{    DLinkList p = NULL, q = L;    while(q->next != L && i >= 1)                  //直到第i个结点    {        p = q;                                  //p为q的前驱        q = q->next;        i--;    }    p->next = q->next;    //if(q->next != NULL)                         //非循环链表需要判断是否为最后一个结点        q->next->pre = p;    *e = q->data;    free(q);}void ListTraverse(DLinkList L){    DLinkList p = L;    while(p->next != L)    {        p = p->next;        printf("%d", p->data);    }    printf("\n");}void ListReTraverse(DLinkList L){    DLinkList p = L;    while(p->pre != L)    {        p = p->pre;        printf("%d", p->data);    }    printf("\n");}int main(){    DNode L;    int e;    ListCreate(&L, 3);    ListTraverse(&L);    ListInsert(&L, 1, 0);    ListTraverse(&L);    ListInsert(&L, 5, 7);    ListTraverse(&L);    ListDelete(&L, 1, &e);    ListTraverse(&L);    ListDelete(&L, 4, &e);    ListTraverse(&L);    ListReTraverse(&L);}