所实现的循环单链表的结构例如以下图所看到的：
循环单链表的实现，和上一篇文章单链表的实现大致同样点击打开链接，略有差别：
1：循环推断的条件不再是s == NULL或者s->next == NULL,而是他们是否等于头指针。2: 断开链表时的处理，尾节点的next不是NULL，而是指向头结点
详细细节參考上一篇文章
头文件：SCList.h
#ifndef SCLIST_H
#define SCLIST_H
#include<iostream>
#include<cassert>
using namespace std;
typedef enum{ FALSE, TRUE }Status;
template<class Type>
class List;
template<class Type>
class ListNode
{
friend class List<Type>;
private:
Type data;
ListNode *next;
public:
ListNode() :data(Type()), next(NULL){}
ListNode(Type d, ListNode<Type> *n = NULL) :data(d), next(n){}
void SetData(Type d){ data = d; }
Type GetData()const{ return data; }
~ListNode(){}
};
template<class Type>
class List
{
private:
ListNode<Type> *first;
ListNode<Type> *last;
size_t size;
public:
List()
{
ListNode<Type> *s = new ListNode<Type>;
assert(s != NULL);
first = last = s;
last->next = first;
}
~List()
{
destory();
}
Status push_back(const Type &x)
{
ListNode<Type> *s = new ListNode<Type>(x);
if (s == NULL)
return FALSE;
last->next = s;
last = s;
last->next = first;
size++;
return TRUE;
}
void show_list()
{
ListNode<Type> *s = first->next;
while (s != first)
{
cout << s->data << "->";
s = s->next;
}
cout << "Nul." << endl;
}
Status push_front(const Type &x)
{
ListNode<Type> *s = new ListNode<Type>(x);
if (s == NULL)
return FALSE;
s->next = first->next;
first->next = s;
if (size == 0)
{
last = s;
last->next = first;//---------------->能够省略，think
}
size++;
return TRUE;
}
Status pop_back()
{
if (size == 0)//
{
cout << "循环单链表已空，无法尾删" << endl;
return FALSE;
}
ListNode<Type> *s = first;
while (s->next != last)
s = s->next;
delete last;
last = s;
last->next = first;
size--;
return TRUE;
}
Status pop_front()
{
if (size == 0)//
{
cout << "循环单链表已空。无法头删" << endl;
return FALSE;
}
ListNode<Type> *s = first->next;
first->next = s->next;
delete s;
if (size == 1)
{
last = first;
last->next = first;//能够省略-------------->
}
size--;
return TRUE;
}
Status insert_val(const Type &x)
{
ListNode<Type> *s = first;
while (s->next != first && s->next->data < x)
s = s->next;
if (s->next == first)
push_back(x);
else
{
ListNode<Type> *p = new ListNode<Type>(x);
assert(p != NULL);
p->next = s->next;
s->next = p;
size++;
}
return TRUE;
}
ListNode<Type>* find(const Type &x)
{
if (size == 0)
return NULL;
ListNode<Type> *s = first->next;
while (s != first)
{
if (s->data == x)
return s;
s = s->next;
}
return NULL;
}
Status delete_val(const Type &x)
{
ListNode<Type> *s = find(x);
if (s == NULL)
{
cout << "该元素不存在，无法删除" << endl;
return FALSE;
}
if (s == last)
{
pop_back();
}
else
{
ListNode<Type> *p = s->next;
s->data = p->data;
s->next = p->next;
if (p == last)//------------------->>注意
{
last = s;
}
delete p;
size--;
}
return TRUE;
}
//从第一个节点处断开，一分为二，头结点和第一个节点成为一个单独的循环单链表
//将剩余的节点依次按值插入该链表
void sort()
{
if (size == 0 || size == 1)
return;
ListNode<Type> *s = first->next;
ListNode<Type> *p = s->next;
last = s;
last->next = first;
while (p != first)
{
s = p;
p = p->next;
//insert_val(s->data);
//delete s;
ListNode<Type> *q = first;
while (q->next != NULL && q->next->data < s->data)
{
q = q->next;
}
if (q->next == NULL)
{
last->next = s;
last = s;
last->next = first;
}
else
{
s->next = q->next;
q->next = s;
}
}
}
//从第一个节点处断开，一分为二，头结点和第一个节点成为一个单独的循环单链表
//将剩余的节点依次进行头插
void reserve()
{
if (size == 0 || size == 1)
return;
ListNode<Type> *s = first->next;
ListNode<Type> *p = s->next;
last = s;
last->next = first;
while (p != first)
{
s = p;
p = p->next;
s->next = first->next;
first->next = s;
}
}
size_t lenth()
{
return size;
}
void clear()
{
if (size == 0)
return;
ListNode<Type> *s = first->next;
while (s != first)
{
if (size == 1)
{
last = first;
last->next = first;
}
else
{
first->next = s->next;
}
delete s;
size--;
s = first->next;
}
}
ListNode<Type>* next(ListNode<Type> *s)
{
if (s == last)//最后一个节点没有后继
return NULL;
else
return s->next;
}
ListNode<Type>* prio(ListNode<Type> *s)
{
if (s == first->next)//第一个节点没有前驱
return NULL;
ListNode<Type> *p = first;
while (p->next != s)
{
p = p->next;
}
return p;
}
void destory()
{
clear();
delete first;
first = last = NULL;
}
};
#endif測试文件：main.cpp
#include"SCList.h"
int main()
{
List<int> mylist;
int item;
int n;
int select = 1;
//ListNode<int> *p;
while (select)
{
cout << "*************************************** *" << endl;
cout << "*[1] push_back [2] push_front *" << endl;
cout << "*[3] show_list [4] pop_back *" << endl;
cout << "*[5] pop_front [6] insert_val *" << endl;
cout << "*[7] lenth [8] find *" << endl;
cout << "*[9] merge [10] delete_val*" << endl;
cout << "*[11] sort [12] reserve *" << endl;
cout << "*[13] next [14] clear *" << endl;
cout << "*[15] prio [0] quit_system*" << endl;
cout << "请选择：>";
cin >> select;
switch (select)
{
case 1:
cout << "请输入要插入的元素（-1结束):>";
while (cin >> item, item != -1)
{
mylist.push_back(item);
}
break;
case 2:
cout << "请输入要插入的元素（-1结束）:>";
while (cin >> item, item != -1)
{
mylist.push_front(item);
}
break;
case 3:
mylist.show_list();
break;
case 4:
mylist.pop_back();
break;
case 5:
mylist.pop_front();
break;
case 6:
cout << "请输入要插入的元素：";
cin >> item;
mylist.insert_val(item);
break;
case 7:
cout << "长度为：" << mylist.lenth() << endl;
break;
case 8:
cout << "请输入要查找的元素：";
cin >> item;
if (mylist.find(item))
cout << "it's found" << endl;
else
cout << "it's not exist" << endl;
break;
case 9:
cout << "请输入要删除的位置：";
cin >> n;
//mylist.delete_pos(n,item);
break;
case 10:
cout << "请输入要删除的元素：";
cin >> item;
mylist.delete_val(item);
break;
case 11:
mylist.sort();
break;
case 12:
mylist.reserve();
break;
case 13:
cout << "请输入要查找后继的元素：";
cin >> item;
//p = mylist.next(item);
//if (p != NULL)
// cout << p->GetData() << endl;
break;
case 14:
mylist.clear();
break;
default:
break;
}
}
system("pause");
return 0;
}