C++实现优先队列

/***********优先队列的(单向)链式实现形式*************/
节点类
template
class QueueNode
{
public:
Type data;//数据
int priority;//优先级
QueueNode *next;
QueueNode() :data(Type()), priority(0), next(nullptr){}
QueueNode(Type d, int p, QueueNode *n=nullptr) :data(d), priority(p), next(n){}
};
//优先队列类
template
class Priority_Queue
{
private:
QueueNode *front;//队头指针
QueueNode *rear;//队尾指针
int length;//队列长度
public:
Priority_Queue();
~Priority_Queue();
bool isEmpty(){ return this->length == 0; }
int size() const { return this->length; }
bool Push(const Type &d, int p);
bool Pop();
Type GetHead();
void ShowQueue() const;
};
//构造函数
template
Priority_Queue::Priority_Queue() :length(0)
{
cout << “构造函数，创建一个节点” << endl;
this->front = this->rear = new QueueNode();
}
//析构函数
template
Priority_Queue::~Priority_Queue()
{
cout << “析构函数” << endl;
QueueNode *dnode = this->front;
QueueNode *tmp = this->front;
while (tmp != nullptr)
{
tmp = tmp->next;
delete dnode;
dnode = tmp;
}

}
//添加节点
template
bool Priority_Queue::Push(const Type &d, int p)
{
QueueNode *add = new QueueNode(d, p, nullptr);//将要插入的节点
if (add == nullptr)
return false;
//要根据优先级构造队列，数字越小优先级越高应该， 数字最小的应该放在最前面
if (this->front == this->rear)
{
cout << “该队列为空，直接将节点插入即可” << endl;
this->rear->next = add;
this->rear = add;
this->length++;
return true;
}
QueueNode *move = this->front->next;//移动指针找到第一个比塔优先级小的节点
while (move->priority < add->priority && move != nullptr)
move = move->next;
if (move == nullptr)//说明队列中的优先级都比add大，直接将节点插在队尾即可
{
this->rear->next = add;
this->rear = add;
this->length++;
return true;
}
QueueNode *tmp = this->front;
while (tmp->next != move)
tmp = tmp->next;
add->next = move;
tmp->next = add;
this->length++;
return true;
}
template
bool Priority_Queue::Pop()
{
if (this->length == 0)
{
cout << “队列为空，无法输出” << endl;
return false;
}
QueueNode *dnode = this->front->next;
this->front->next = dnode->next;
if (this->length == 1)
this->rear = this->front;
delete dnode;
this->length–;
return true;
}
template
Type Priority_Queue::GetHead()
{
if (this->length == 0)
{
cout << “队列为空，无法获得第一个元素的值” << endl;
return 0;
}
return this->front->next->data;
}
template
void Priority_Queue::ShowQueue() const
{
if (this->length == 0)
{
cout << “队列为空，无法输出” << endl;
return;
}
QueueNode *move = this->front->next;
int i = 0;
while (move != nullptr)
{
cout << “第” << i + 1 << “个元素输出: ” << endl
<< “data:” << move->data << endl
<< “priority:” << move->priority << endl;
move = move->next;
i++;
}
}
//测试程序
int main()
{
Priority_Queue queue;
for (int i = 0, j = 10; i < 10, j>0; i++, j–)
queue.Push(i + 1, j);
queue.Push(100, 4);
//queue.ShowQueue();
for (int i = 0; i < 5; i++)
queue.Pop();
queue.ShowQueue();
return 0;
}

/***********优先队列的(双向)链式实现形式*************/
//队列节点类
template
class QueueNode
{
public:
Type data;//数据域
int priority;//优先级
QueueNode *next;//后继指针
QueueNode *prev;//前向指针
QueueNode() :data(Type()), priority(0), next(nullptr), prev(nullptr){}
QueueNode(Type d, int pri, QueueNode *n = nullptr, QueueNode *p = nullptr) :data(d), priority(pri), next(n), prev(p){}
};
//优先队列类
template
class Priority_Queue
{
private:
QueueNode *front;//头指针
QueueNode *rear;//尾指针
int length;//队列长度
public:
Priority_Queue();
~Priority_Queue();
bool isEmpty(){ return this->length == 0; }
int size() const { return this->length; }
bool Push(const Type &d, int p);
bool Pop();
Type GetHead();
void ShowQueue() const;
};
//构造函数
template
Priority_Queue::Priority_Queue() :length(0)
{
cout << “构造函数,创建一个头节点” << endl;
this->front = this->rear = new QueueNode();
}
//析构函数
template
Priority_Queue::~Priority_Queue()
{
cout << “析构函数” << endl;
/*QueueNode *dnode = this->front;
QueueNode move = this->front;/
}
//添加节点
template
bool Priority_Queue::Push(const Type &d, int p)
{
QueueNode *add = new QueueNode(d, p, nullptr, nullptr);//将要插入的节点
if (add == nullptr)
return false;
if (this->length == 0)
{
//cout << “链表为空，直接插入即可” << endl;
this->front->next = add;
add->prev = this->front;
this->rear = add;
this->length++;
return true;
}
//加入链表不为空，排序添加节点
QueueNode *move = this->front->next;
while (move->priority < add->priority && move != nullptr)
move = move->next;
if (move == nullptr)
{
//说明队列中所有元素的优先级都比add大，直接插在队后即可
this->rear->next = add;
add->prev = this->rear;
this->rear = add;
this->length++;
return true;
}
move->prev->next = add;
add->prev = move->prev;
add->next = move;
move->prev = add;
this->length++;
return true;
}
//删除节点
template
bool Priority_Queue::Pop()
{
if (this->length == 0)
{
cout << “队列为空，无法删除” << endl;
return false;
}
if (this->length == 1)
{
delete this->front->next;
this->front->next = nullptr;
this->rear = nullptr;
this->length–;
return true;
}
QueueNode *dnode = this->front->next;
this->front->next = dnode->next;
dnode->next->prev = this->front;
delete dnode;
this->length–;
return true;
}
//获取第一个元素的值
template
Type Priority_Queue::GetHead()
{
if (this->length == 0)
{
cout << “队列为空，无法查看第一个元素的值” << endl;
return 0;//返回0是没有元素
}
return this->front->next->data;
}
//输出队列
template
void Priority_Queue::ShowQueue() const
{
if (this->length == 0)
{
cout << “队列为空，无法删除” << endl;
return;
}
QueueNode *move = this->front->next;
int i = 0;
while (move != nullptr)
{
cout << “第” << i + 1 << “个元素输出: ” << endl
<< “data:” << move->data << endl
<< “priority:” << move->priority << endl;
move = move->next;
i++;
cout << endl;
}
}
//测试程序
int main()
{
Priority_Queue queue;
for (int i = 0, j = 10; i<10, j>0; i++, j–)
queue.Push(i, j);
queue.Push(1, 2);
//queue.Pop();
queue.ShowQueue();
return 0;
}