双向循环链表

/******************************************
    双向循环链表的实现
    by Rowandjj
    date:2014.4.1
******************************************/
#include<iostream>
using namespace std;

#define OVERFLOW -1

typedef int ElemType;
/*线性表的双向链表存储结构*/
typedef struct _DULNODE_
{
    ElemType data;
    struct _DULNODE_ *prior;
    struct _DULNODE_ *next;
}DulNode,*DuLinkList,*pDulNode;

/***************操作定义******************/

void InitList(DuLinkList &L);//产生空的双向循环链表
int DestroyList(DuLinkList &L);//销毁双向循环链表
int ClearList(DuLinkList &L);//将表清空
int ListEmpty(DuLinkList L);//判断链表是否为空
int ListLength(DuLinkList L);//返回链表长度
int GetElem(DuLinkList L,int i,ElemType &e);//获取指定位置的元素的值并赋给e
int LocateElem(DuLinkList L,ElemType e,int (*compare)(ElemType,ElemType));//返回L中第1个与e满足关系compare()的数据元素的位序
int PriorElem(DuLinkList L,ElemType cur_e,ElemType &pre_e);//返回元素前驱
int NextElem(DuLinkList L,ElemType cur_e,ElemType &next_e);//返回元素后继
int ListInsert(DuLinkList &L,int i,ElemType e);//插入元素
int ListDelete(DuLinkList &L,int i,ElemType &e);//删除元素，用e返回
void ListTraverse(DuLinkList L,void(*visit)(ElemType));//顺序遍历链表

DuLinkList GetElemP(DuLinkList L,int i);//在双向链表L中返回第i个元素的位置指针
int compare(ElemType e1,ElemType e2);
void visit(ElemType e);

void CreateList(DuLinkList &L,int n);
/***************具体实现*******************/
void InitList(DuLinkList &L)
{
    L = (pDulNode)malloc(sizeof(DulNode));
    if(!L)
    {
        exit(OVERFLOW);
    }
    L->next = L->prior = L;
}
int DestroyList(DuLinkList &L)
{
    pDulNode q,p = L->next;
    while(p!=L)
    {
        q = p->next;
        free(p);
        p = q;
    }
    free(L);
    L = NULL;
    return 1;
}
int ClearList(DuLinkList &L)
{
    pDulNode q,p = L->next;
    while(p != L)
    {
        q = p->next;
        free(p);
        p = q;
    }
    L->next = L->prior = L;
    return 1;
}
int ListEmpty(DuLinkList L)
{
    return L->next == L && L->prior == L;
}
int ListLength(DuLinkList L)
{
    pDulNode p = L->next;
    int count = 0;
    while(p != L)
    {
        p = p->next;
        count++;
    }
    return count;
}
int GetElem(DuLinkList L,int i,ElemType &e)
{
    pDulNode p = L->next;
    int j = 1;
    while(j < i && p != L)
    {
        j++;
        p = p->next;
    }
    if(j>i || p == L)
    {
        return 0;
    }
    e = p->data;
    return 1;
}
int LocateElem(DuLinkList L,ElemType e,int (*compare)(ElemType,ElemType))
{
    pDulNode p = L->next;
    int i = 0;
    while(p != L)
    {
        i++;
        if(compare(e,p->data))
        {
            return i;
        }
        p = p->next;    
    }
    return 0;
}

int compare(ElemType e1,ElemType e2)
{
    return e1 == e2;
}

int PriorElem(DuLinkList L,ElemType cur_e,ElemType &pre_e)
{
    if(ListEmpty(L))
    {
        return 0;
    }
    pDulNode p = L->next->next;
    if(p == L)
    {
        return 0;
    }
    while(p != L)
    {
        if(p->data == cur_e)
        {
            pre_e = p->prior->data;
            return 1;
        }
        p = p->next;
    }
    return 0;
}

int NextElem(DuLinkList L,ElemType cur_e,ElemType &next_e)
{
    if(ListEmpty(L))
    {
        return 0;
    }
    pDulNode p = L->next->next;
    if(p == L)
    {
        return 0;
    }
    while(p != L)
    {
        if(p->prior->data == cur_e)
        {
            next_e = p->data;
            return 1;
        }
        p = p->next;
    }
    return 0;
}
DuLinkList GetElemP(DuLinkList L,int i)
{
    int j;
    pDulNode p = L;
    for( j = 1; j<= i;j++)
    {
        p = p->next;
    }
    return p;
}
int ListInsert(DuLinkList &L,int i,ElemType e)
{
    if(i < 1 || i > ListLength(L)+1)
    {
        return 0;
    }
    pDulNode p = GetElemP(L,i-1);

    if(!p)
    {
        return 0;
    }
    pDulNode q = (pDulNode)malloc(sizeof(DulNode));
    if(!q)
    {
        return 0;
    }
    q->data = e;
    q->next = p->next;
    q->prior = p;
    p->next->prior = q;
    p->next = q;
    return 1;
}
int ListDelete(DuLinkList &L,int i,ElemType &e)
{
    if(i<1 || i>ListLength(L))
    {
        return 0;
    }
    pDulNode p = GetElemP(L,i);
    if(!p)
    {
        return 0;
    }
    e = p->data;
    p->prior->next = p->next;
    p->next->prior = p->prior;

    return 1;
}
void ListTraverse(DuLinkList L,void (*visit)(ElemType))
{
    pDulNode p = L->next;
    while(p != L)
    {
        visit(p->data);
        p = p->next;
    }
    cout<<endl;
}
void CreateList(DuLinkList &L,int n)
{
    if(n <= 0)
    {
        return;
    }
    ElemType e;
    for(int i = 0; i < n; i++)
    {
        cin>>e;
        pDulNode p = (pDulNode)malloc(sizeof(DulNode));
        if(!p)
        {
            return;
        }
        p->next = L->next;
        p->prior = L;
        L->next->prior = p;
        L->next = p;
        p->data = e;
    }

}
void visit(ElemType e)
{
    cout<<e<<" ";
}