数据结构双向链表的基本操作，包括创立，删除，添加和遍历等

最近在写双向链表，看了好长时间也没有成功，就在网上查了一个，感觉还不错，就转载了看看，仔细研究研究

#include "stdafx.h"

#include<stdio.h>

#include<stdlib.h>

#define TRUE   1

#define FALSE  0

#define OK     1

#define ERROR  0

typedef int status;

typedef int ElemType;

typedef struct Node {
ElemType data;
struct Node *prior, *next;

}Lnode, *LinkList;

typedef struct {
LinkList head, tail;
int len;

}DuLinkList;

void Build(DuLinkList &L)

{
int n, x;
LinkList p, q;
L.head = (LinkList)malloc(sizeof(Lnode));
L.tail = (LinkList)malloc(sizeof(Lnode));
L.head->next = L.tail;
L.tail->prior = L.head;
p = L.head;
printf("请输入n和n个数据元素\n");
scanf_s("%d", &n);
L.len = n;
while (n--)
{
q = (LinkList)malloc(sizeof(Lnode));
scanf_s("%d", &x);
q->data = x;
q->next = L.tail;
L.tail->prior = q;
q->prior = p;
p->next = q;
p = q;
}

}

void Print1(DuLinkList &L)//正向遍历输出

{
LinkList p;
p = L.head->next;
while (p != L.tail)
{
printf("%d ", p->data);
p = p->next;
}
printf("\n长度为:%d\n", L.len);

}

void Print2(DuLinkList &L)//逆向遍历输出

{
LinkList p;
p = L.tail->prior;
while (p != L.head)
{
printf("%d ", p->data);
p = p->prior;
}
printf("\n长度为:%d\n", L.len);

}

void Tips()

{
printf("按数字键选择相应操作\n");
printf("1、正向遍历输出\n");
printf("2、逆向遍历输出\n");
printf("3、删除值为X的元素\n");
printf("4、插入值为X的元素，使仍然有序\n");
printf("5、判断双向链表中元素是否对称若对称\n");
printf("6、把所有奇数排列在偶数之前\n");
printf("0、退出\n");

}

status Delete(DuLinkList &L, int x)

{
LinkList p, q;
p = L.head;
while (p->next != L.tail && p->next->data != x)
p = p->next;
if (p->next != L.tail)
{
q = p->next;
p->next = q->next;
q->next->prior = p;
free(q);
L.len--;
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span style="white-space:pre;">return OK;
}
return ERROR;

}

status Insert(DuLinkList &L, int x)

{
LinkList p, q;
p = L.head;
while (p->next != L.tail && p->next->data<x)
p = p->next;
q = (LinkList)malloc(sizeof(Lnode));
q->data = x;
q->prior = p;
q->next = p->next;
p->next->prior = q;
p->next = q;
L.len++;
return OK;

}

status Judge(DuLinkList &L)

{
//p从头结点开始，q从尾结点开始，依次比较p->data和q->data
int i;
LinkList p, q;
p = L.head->next;
q = L.tail->prior;
for (i = 0; i<L.len / 2; i++)
{
if (p->data != q->data)
break;
p = p->next;
q = q->prior;
}
if (i == L.len / 2)
return OK;
return ERROR;

}

status PaiLie(DuLinkList &L)

{
//把所有的奇数结点都移到以s为头结点的链表上
LinkList s, p, q, r;
p = L.head;
s = (LinkList)malloc(sizeof(Lnode));
s->next = NULL;
r = s;
while (p->next != L.tail)
{
if (p->next->data & 1)
{
r->next = p->next;
p->next->prior = r;
p->next = p->next->next;
p->next->prior = p;
r = r->next;
}
else
p = p->next;
}
//把链表s接到L.head
r->next = L.head->next;
L.head->next->prior = r;
L.head->next = s->next;
s->next->prior = L.head;
return OK;

}

int main()

{
DuLinkList L;
int op, x, flag;
Build(L);
Tips();
scanf_s("%d", &op);
while (op)
{
switch (op)
{
case 1:
Print1(L);
break;
case 2:
Print2(L);
break;
case 3:
printf("请输入要删除的x\n");
scanf_s("%d", &x);
flag = Delete(L, x);
if (flag)
printf("删除成功!!\n\n");
else
printf("元素不存在，删除失败!!\n\n");
break;
case 4:
printf("请输入要插入的x\n");
scanf_s("%d", &x);
flag = Insert(L, x);
if (flag)
printf("插入成功!!\n\n");
else
printf("插入失败!!\n\n");
break;
case 5:
flag = Judge(L);
if (flag)
printf("对称!!!\n\n");
else
printf("不对称!!!\n\n");
break;
case 6:
flag = PaiLie(L);
if (flag)
printf("重新排列成功!!!\n\n");
else
printf("重新排列失败!!!\n\n");
break;
default:
printf("输入错误!!!\n\n");
break;

}
Tips();
scanf_s("%d", &op);
}
return 0;

}