C语言或C++实现一个双向有序链表类，可返回指定节点，可实现插入删除操作，且保持序列不变，现在要急急急

Question

C语言或C++实现一个双向有序链表类，可返回指定节点，可实现插入删除操作，且保持序列不变，越简洁越好，现在要急急急
不要复制啊，我这是个面试题，这么多写不上去啊

Answer 1

//CreateList_L.cpp
//To create a LinkList
#include <stdlib.h>
#include <iostream.h>
#include <conio.h>
# define TRUE 1
# define FALSE 0
# define OK 1
# define ERROR 0
# define INFEASIBLE -1
# define OVERFLOW -2

typedef struct DuLNode
{ int data;
struct DuLNode *prior;
struct DuLNode *next;
}DuLNode,*DuLinkList;
// 初始条件：L已存在。操作结果：返回L中数据元素个数
int ListLength(DuLinkList L)
{
int i=0;
DuLinkList p=L->next; // p指向第一个结点
while(p!=L) // p没到表头
{
i++;
p=p->next;
}
return i;
}

// 由双链循环线性表L的头结点出发,正序输出每个数据元素
void ListTraverse(DuLinkList L)
{
DuLinkList p=L->next;
while(p!=L)
{
cout<<p->data<<"\t";
p=p->next;
}
cout<<endl;
}
// 由双链循环线性表L的头结点出发,逆序输出每个数据元素
void ListTraverseBack(DuLinkList L)
{
DuLinkList p=L->prior;
while(p!=L)
{
cout<<p->data<<"\t";
p=p->prior;
}
cout<<endl;
}

//To Creatre a DuLinkList L with HeadNode
void CreateList_DuL(DuLinkList &L)
{
int n;
int i;
DuLNode *p;
L=(DuLinkList)malloc(sizeof(DuLNode));
L->next=L->prior=L;
cout<<"CreateList_L"<<endl<<"================"<<endl;
cout<<"Please input the Init DuLinkNode Number: <eg. 5> ";
cin>>n;

cout<<"Please input the data for DuLinkList Nodes: <eg. 34,67,3,-9,45,...>"<<endl;
for(i=n;i>0;--i)
{
p=(DuLinkList)malloc(sizeof(DuLNode));
cin>>p->data; //Reverse order inputing for Creating a LinkList
p->prior=L;
p->next=L->next;
L->next->prior=p;
L->next=p;
}
if(n)
{
cout<<endl;
cout<<"Success to Create a DuLinkList !"<<endl;
ListTraverse(L);
cout<<endl;
}
else cout<<"A NULL DuLinkList have been created !"<<endl;
}

//ListInsert_Dul()
int ListInsert_DuL(DuLinkList &L)
{
DuLNode *p=L,*s;
int j=0;
int i;
int e;
cout<<"======"<<"before insert:"<<"======"<<endl;
ListTraverse(L);
cout<<"input the location you want to insert:";
cin>>i;
while (i<1||i>ListLength(L)+1)
{
//i值不合法
cout<<"illeagle location,please input the correct location:";
cin>>i;
}

cout<<"input the number you want to insert:";
cin>>e;
while(j<i)
{ p=p->next;
++j;
}
if(!(s=(DuLinkList)malloc(sizeof(DuLNode))))
{
cout<<endl<<"Allocate space failure ! " ;
return (ERROR);
}
s->data=e;
s->prior=p->prior;
s->next=p;
if(i==1)
L->next=s;
p->prior->next=s;
p->prior=s;
cout<<"has insert:"<<e<<endl;
ListTraverse(L);
cout<<"======"<<"after insert:"<<"======"<<endl<<endl;
return (OK);
}

// 删除带头结点的双链循环线性表L的第i个元素,i的合法值为1≤i≤表长
int ListDelete(DuLinkList L)
{
DuLinkList p;
int j=1; // j为计数器
int e;
int i;

cout<<"input the location of the number you want to delete"<<endl;
cin>>i;
while(i<0||i>ListLength(L))
{
//i值不合法
cout<<"illeagle location,please input the correct location:";
cin>>i;
}

p=L->next; // p指向第一个结点
while(p!=L&&j<i) // 顺指针向后查找,直到p指向第i个元素或p指向头结点
{
p=p->next;
j++;
}
if(p==L||j>i) // 第i个元素不存在
{
cout<<"第i个元素不存在"<<endl;
return ERROR;
}
else
{
cout<<"======"<<"before delete:"<<"======"<<endl;
ListTraverse(L);
e=p->data; // 取第i个元素
if(!p) // p=NULL,即第i个元素不存在
return ERROR;
e=p->data;
p->prior->next=p->next;
p->next->prior=p->prior;
free(p);
cout<<"has delete:"<<e<<endl;
ListTraverse(L);
cout<<"======"<<"after delete:"<<"======"<<endl<<endl;
return OK;
}

}
void menu(int c)
{
cout<<"================================================="<<endl;
cout<<"\t\t1----建立"<<endl;
cout<<"\t\t2----插入"<<endl;
cout<<"\t\t3----删除"<<endl;
cout<<"\t\t4----逆置"<<endl;
//cout<<"\t\t5----菜单"<<endl;
cout<<"\t\t0----退出"<<endl;
cout<<"================================================="<<endl;
cout <<endl<<"input you choice number:";
}
void main()
{
DuLinkList L;
int c=1;

while(c!=0)
{
switch(c)
{
case 0:
break;
case 1:
CreateList_DuL(L);
break;
case 2:
ListInsert_DuL(L);
break;
case 3:
ListDelete(L);
break;
case 4:
ListTraverseBack(L);
break;
default:
cout<<"infeasible choice,input again:"<<endl;
menu(c);
cin>>c;
}
if(c!=0)
{
menu(c);
cin>>c;
}
}
}追问

不要复制啊，我这是个面试题，这么多写不上去啊