单循环链表的实现

//circular_linked_list .h  头文件
#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>
#include<stdlib.h>
typedef struct round
{
int data;
struct round *pNext;
}NODE, *PNODE;

PNODE create();

void judge(PNODE phead);

void traverse_list(PNODE pHead);

int is_empty(PNODE pHead);

int lenght_list(PNODE pHead);

int insert_list(PNODE pHead, int n, int val);

int delete_list(PNODE pHead, int n, int *pVal);

void soert_list(PNODE pHead, char ch);

int*  find(PNODE pHead, int a, int *sv);

PNODE DestroyList(PNODE pHead);

#define _CRT_SECURE_NO_WARNINGS 1

#include"circular_linked_list .h"

//判断malloc是否开辟成功
void judge(PNODE phead)
{
if (phead == NULL)
{
printf("动态开辟失败");
exit(1);
}
}

//创建循环链表
PNODE create()
{
int count = 0;
int val = 0;
PNODE phead = (PNODE)malloc(sizeof(NODE));
phead->pNext = phead;
judge(phead);
PNODE ptail = phead;
ptail->pNext = NULL;
printf("输入你所需要创建的节点个数：");
scanf("%d", &count);
for (int i = 0; i < count; i++)
{
PNODE pnew = (PNODE)malloc(sizeof(NODE));
judge(pnew);
printf("输入在第%d节点的值：", i + 1);
scanf("%d", &val);
pnew->data = val;
ptail->pNext = pnew;
pnew->pNext =phead;
ptail = pnew;

}
return phead;
}

//遍历整个循环链表
void traverse_list(PNODE phead)
{
judge(phead);
PNODE p = phead->pNext;
while (p!=phead)
{
printf("%d  ", p->data);
p = p->pNext;
}
printf("\n");
}

//判断链表是否为空
int is_empty(PNODE pHead)
{
if (pHead == pHead->pNext)
{
return 1;
}

return 0;
}

//求链表的长度
int lenght_list(PNODE pHead)
{
int len = 0;
judge(pHead);
PNODE p = pHead->pNext;
while (p)
{
if (p != pHead)
{
len++;
p = p->pNext;
}
else
break;
}
return len;
}

//插入在某个位置插入数据
int insert_list(PNODE pHead, int n, int val)
{
judge(pHead);
PNODE p = pHead;
int i = 0;
//在这里进行的是寻找咱们所需要插入的那个节点
while (NULL != p&&i < n - 1)
{
p = p->pNext;
i++;
}

if (n <= 0 || n>lenght_list(pHead))
{
return 0;
}
PNODE pNew = (PNODE)malloc(sizeof(NODE));
judge(pNew);
pNew->data = val;
pNew->pNext = p->pNext;
p->pNext = pNew;
if (p == pHead)
pHead = pNew;
return 1;
}

//删除指定位置节点
int delete_list(PNODE pHead, int n, int *pVal)
{
judge(pHead);
PNODE p = pHead;
int i = 0;
while (i<n-1)
{
p = p->pNext;
i++;
}
if (n <= 0 || n>lenght_list(pHead))
{
return 0;
}
PNODE q = p->pNext;
*pVal = q->data;
//输出p节点后的节点，这里要注意的是一定要记得free；
p->pNext = q->pNext;
if (pHead == q)
pHead = q;
free(q);
return 1;
}

//链表排序
//链表排序最适合的是冒泡排序法。
void soert_list(PNODE pHead,char ch)
{
judge(pHead);
if ('>'==ch)
{
for (PNODE p1 = pHead->pNext; p1 != pHead; p1=p1->pNext)
{
for (PNODE p2 = pHead->pNext; p2 != pHead; p2 = p2->pNext)
{
if ((p1->data) > (p2->data))
{
int tmp = p1->data;
p1->data = p2->data;
p2->data = tmp;
}
}
}
}
else if ('<' == ch)
{
for (PNODE p1 = pHead->pNext; p1 != pHead; p1 = p1->pNext)
{
for (PNODE p2 = pHead->pNext; p2 != pHead; p2 = p2->pNext)
{
if ((p1->data) < (p2->data))
{
int tmp = p1->data;
p1->data = p2->data;
p2->data = tmp;
}
}
}
}
}

//查找某个元素的位置
int*  find(PNODE pHead, int a, int *sv)
{
judge(pHead);
int count = 1;
PNODE p = pHead->pNext;
while (p !=pHead)
{
p = p->pNext;
count++;
if (a == p->data)
{
*sv = count;
return sv;
}
}
return NULL;
}

//销毁链表
PNODE DestroyList(PNODE pHead)
{
PNODE q, p ;
p = q = NULL;
p = pHead;
while (p->pNext != pHead)
{
q = p->pNext;//让q指向下一个节点
p ->pNext= q->pNext;//p存储了q。下一个节点的地址；
free(q);
}
free(pHead);
return NULL;
}

#define _CRT_SECURE_NO_WARNINGS 1

#include<stdio.h>
#include<stdlib.h>
#include"circular_linked_list .h"
int main()
{
int len = 0;
//接下来进行循环链表的操作
//首先创建循环链表
PNODE phead = NULL;

//测试创建循环链表
phead=create(phead);

//测试遍历循环链表
traverse_list(phead);

//测试判断链表是否为空
if (is_empty(phead) == 0)
printf("链表非空\n");
else
printf("链表为空\n");

//测试求循环链表的长度
printf("此循环链表的长度为：\n");
len = lenght_list(phead);
printf("%d\n",len);

//测试插入在某个位置插入数据
int n = 0;
int val = 0;
printf("请输入你所需要插入的位置:");
scanf("%d", &n);
printf("请输入你所需要插入的数据:");
scanf("%d", &val);
if (insert_list(phead, n, val) == 0)
printf("插入失败\n");
else
printf("插入成功\n");
traverse_list(phead);

//测试删除指定位置的节点
int del_Val = 0;
printf("请输入你所需要删除的节点所在的位置：");
scanf("%d", &n);
if (delete_list(phead, n, &del_Val))
{

printf("删除元素%d成功\n", del_Val);
}
else
{
printf("删除元素%d失败\n", del_Val);
}
traverse_list(phead);

//测试链表元素查找,并且返回所在位置
int a = 0;
int find_position = 0;
printf("输入你所要查找的元素");
scanf("%d", &a);
if (find(phead, a, &find_position) == NULL)
printf("该循环链表中没有这一个元素。\n");
else
{
printf("所查找的元素位置位于：\n");
printf("%d\n", find_position);
}

//测试循环链表的排序
char ch = 0;
printf("选择循环链表的排序方式(输入'>'或者'<'):\n");
fflush(stdin);
scanf("%c",&ch);
soert_list(phead,ch);
traverse_list(phead);

//测试销毁链表
phead=DestroyList(phead);
traverse_list(phead);

system("pause");
return 0;

}