C++实现双向循环链表
/***********双向循环链表（代码调试正常，所有功能均测试）*************/
//节点类
template
class ListNode
{
public:
Type data;//节点数据域
ListNode *next;//后继指针
ListNode *prev;//前驱指针
ListNode() :data(Type()), next(nullptr), prev(nullptr){}
ListNode(Type d, ListNode *n = nullptr, ListNode *p = nullptr) : data(d), next(n), prev(p){}
void SetData(Type d){ this->data = d; }
};
//双向循环链表:主要注意尾指针的调节
template
class DoubleList
{
private:
ListNode *head;//链表头指针
ListNode *tail;//链表尾指针
int length;//链表长度
public:
DoubleList();
~DoubleList();
bool isEmpty(){ return this->length == 0; }
int size(){ return this->length; }
bool push_front(const Type &x);
bool push_back(const Type &x);
bool push_val(int k, const Type &x);//在链表第K个位置插入元素X
bool pop_front();
bool pop_back();
bool pop_data(int k);//删除第k个节点
bool find(int k, Type &x) const;
void reserse();
void show_list() const;
};
//构造函数
template
DoubleList::DoubleList()
{
cout << “构造函数(空链表，包含一个头节点)” << endl;
this->head = this->tail = new ListNode();
this->head->prev = this->tail;
this->tail->next = this->head;
this->length = 0;
}
//析构函数
template
DoubleList::~DoubleList()
{
cout << “析构函数，删除所有节点” << endl;
ListNode *pdelete, *ptemp;
pdelete = this->head->next;
while (pdelete != this->head)
{
ptemp = pdelete->next;
this->head->next = ptemp;
ptemp->prev = this->head;
delete pdelete;
pdelete = ptemp;
}
delete this->head;
}
//头插
template
bool DoubleList::push_front(const Type &x)
{
ListNode *temp = new ListNode(x, nullptr, nullptr);//创建一个节点
if (temp == nullptr)
return false;
if (this->length == 0)//判断this->head->prev==this->head
{
this->head->next = temp;
temp->prev = this->head;
this->tail = temp;
this->tail->next = this->head;
this->head->prev = this->tail;
this->length++;
return true;
}
temp->next = this->head->next;
this->head->next->prev = temp;
temp->prev = this->head;
this->head->next = temp;
this->length++;
return true;
}
//尾插
template
bool DoubleList::push_back(const Type &x)
{
ListNode *temp = new ListNode(x, nullptr, nullptr);
if (temp == nullptr)
return false;
this->tail->next = temp;
temp->prev = this->tail;
this->tail = temp;
this->tail->next = this->head;
if (this->length == 0)
this->head->prev = this->tail;
this->length++;
return true;
}
//在链表中第k个位置之前，插入新的节点
template
bool DoubleList::push_val(int k, const Type &x)
{
if (k<1 || k>this->length)
{
cout << “插入的数据不在范围内” << endl;
return false;
}
ListNode *temp = new ListNode(x, nullptr, nullptr);//创建一个节点对象
//首先找到第k个节点
ListNode *move = this->head->next;
int i = 1;
while (i < k)
{
move = move->next;
i++;
}
//move是指向第k个节点
move->prev->next = temp;
temp->prev = move->prev;
temp->next = move;
move->prev = temp;
return true;
}
//删除链表开始的节点
template
bool DoubleList::pop_front()
{
if (this->length == 0)
{
cout << “链表为空，无法删除” << endl;
return false;
}
ListNode *temp = this->head->next;//保存第一个节点的地址
this->head->next = temp->next;
temp->next->prev = this->head;
delete temp;
if (this->length == 1)//考虑只有一个元素的特殊情况
this->tail = this->head;
this->length–;
return true;
}
//删除链表最后一个元素
template
bool DoubleList::pop_back()
{
if (this->length == 0)
{
cout << “链表为空，无法删除” << endl;
return false;
}
this->tail->prev->next = this->head;
this->head->prev = this->tail->prev;
delete this->tail;
this->tail = this->head->prev;
this->length–;
return true;
}
//删除第k个节点
template
bool DoubleList::pop_data(int k)
{
if (k<0 || k>this->length)
{
cout << “删除的位置不在范围内，无法删除” << endl;
return false;
}
ListNode *move = this->head->next;
int i = 1;
while (i < k)
{
move = move->next;
i++;
}
if (k == this->length)
{
pop_back();
return true;
}
move->prev->next = move->next;
move->next->prev = move->prev;
delete move;
this->length–;
return true;
}
//查找元素
template
bool DoubleList::find(int k, Type &x) const
{
if (k<1 || k>this->length)
{
cout << “查找元素不在范围内，无法查找” << endl;
x = 0;
return false;
}
ListNode *move = this->head->next;
int i = 1;
while (i < k)
{
move = move->next;
i++;
}
x = move->data;
return true;
}
//逆置链表
template
void DoubleList::reserse()
{
if (this->length == 0 || this->length == 1)
{
cout << “链表中有一个或者链表为空，不需要逆置” << endl;
return;
}
ListNode *s = this->head->next;
ListNode *p = s->next;
s->next = this->head;
this->head->prev = s;
this->tail = s;
while (p != this->head)//注意不能判断p!=nullptr 这样循环永远不会停止，循环链表不可能为nullptr
{
s = p;
p = p->next;
s->next = this->head->next;
this->head->next->prev = s;
this->head->next = s;
s->prev = this->head;
}
}
//输出链表
template
void DoubleList::show_list() const
{
if (this->length == 0)
return;
ListNode *move = this->head->next;
while (move != this->head)
{
cout << move->data << ” “;
move = move->next;
}
cout << endl;
}
//测试程序
int main()
{
DoubleList list;
for (int i = 0; i < 10; i++)
list.push_back(i + 1);
list.show_list();
cout << list.size() << endl;
/*int a;
if (list.find(99, a))
cout << “a=” << a << endl;*/
list.reserse();
list.show_list();
cout << list.size() << endl;
/*list.push_val(5, 10);
list.show_list();
cout << list.size() << endl;*/
/*for (int i = 0; i < 5; i++)
list.pop_front();
list.show_list();
cout << list.size() << endl;*/
//for (int i = 0; i < 5;i++)
// list.pop_back();
//list.show_list();
//cout << list.size() << endl;
//list.pop_data(5);
//list.show_list();
return 0;
}