优先级队列

    今天，我们的任务是实现一个优先级队列。

具体实现如下：

Compare.h具体内容如下：

#include <iostream>
using namespace std;

template<typename Type> class Compare{	//处理一般比较大小
public:
	static bool lt(Type item1, Type item2);
};

template<typename Type> bool Compare<Type>::lt(Type item1, Type item2){
	return item1 < item2;
}

struct SpecialData{
	friend ostream& operator<<(ostream&, SpecialData &);
	int m_ntenor;
	int m_npir;
};

ostream& operator<<(ostream& os, SpecialData &out){
	os << out.m_ntenor << "   " << out.m_npir;
	return os;
}

class SpecialCmp{		//处理特殊比较大小,用户可添加适当的类
public:
	static bool lt(SpecialData item1, SpecialData item2);
};

bool SpecialCmp::lt(SpecialData item1, SpecialData item2){
	return item1.m_npir < item2.m_npir;
}

PriorityQueue.h的具体代码如下：

#include "QueueNode.h"
#include "Compare.h"

template<typename Type, typename Cmp> class PriorityQueue{	//Cmp is Designed for compare
public:
	PriorityQueue() :m_prear(NULL), m_pfront(NULL){}
	~PriorityQueue(){
		MakeEmpty();
	}

	void MakeEmpty();               //make the queue empty
	void Append(const Type item);   //insert data
	Type Delete();                  //delete data
	Type GetFront();                //get data
	void Print();                   //print the queue

	bool IsEmpty() const{
		return m_pfront == NULL;
	}


private:
	QueueNode<Type, Cmp> *m_prear, *m_pfront;
};

template<typename Type, typename Cmp> void PriorityQueue<Type, Cmp>::MakeEmpty(){
	QueueNode<Type, Cmp> *pdel;
	while (m_pfront){
		pdel = m_pfront;
		m_pfront = m_pfront->m_pnext;
		delete pdel;
	}
}

template<typename Type, typename Cmp> void PriorityQueue<Type, Cmp>::Append(const Type item){
	if (m_pfront == NULL){
		m_pfront = m_prear = new QueueNode<Type, Cmp>(item);
	}
	else{
		m_prear = m_prear->m_pnext = new QueueNode<Type, Cmp>(item);
	}
}

template<typename Type, typename Cmp> Type PriorityQueue<Type, Cmp>::Delete(){
	if (IsEmpty()){
		cout << "There is no elements!" << endl;
		exit(1);
	}
	QueueNode<Type, Cmp> *pdel = m_pfront, *pmove = m_pfront;
	while (pmove->m_pnext){  //get the minimize priority's data

		//cmp:: lt is used for compare the two data, if the front one 
		//      is less than the back, then return 1
		if (Cmp::lt(pmove->m_pnext->m_data, pdel->m_pnext->m_data)){
			pdel = pmove;
		}
		pmove = pmove->m_pnext;
	}

	pmove = pdel;
	pdel = pdel->m_pnext;
	pmove->m_pnext = pdel->m_pnext;
	Type temp = pdel->m_data;
	delete pdel;
	return temp;
}

template<typename Type, typename Cmp> Type PriorityQueue<Type, Cmp>::GetFront(){
	if (IsEmpty()){
		cout << "There is no elements!" << endl;
		exit(1);
	}
	QueueNode<Type, Cmp> *pdel = m_pfront, *pmove = m_pfront->m_pnext;
	while (pmove){   //get the minimize priority's data
		if (Cmp::lt(pmove->m_data, pdel->m_data)){
			pdel = pmove;
		}
		pmove = pmove->m_pnext;
	}
	return pdel->m_data;
}

template<typename Type, typename Cmp> void PriorityQueue<Type, Cmp>::Print(){
	QueueNode<Type, Cmp> *pmove = m_pfront;
	cout << "front";

	while (pmove){
		cout << "--->" << pmove->m_data;
		pmove = pmove->m_pnext;
	}

	cout << "--->rear" << endl << endl << endl;
}

QueueNode.h具体代码如下：

template<typename Type, typename Cmp> class PriorityQueue;

template<typename Type, typename Cmp>
class QueueNode
{
private:
	friend class PriorityQueue < Type, Cmp > ;
	QueueNode(const Type item, QueueNode<Type, Cmp> *next = NULL)
		:m_data(item), m_pnext(next){}
private:
	Type m_data;
	QueueNode<Type, Cmp> *m_pnext;
};

main.cpp的具体代码如下：

#include <iostream>
#include <cstdlib>
using namespace std;

#include "PriorityQueue.h"

int main(){
	PriorityQueue<int, Compare<int> > queue;
	int init[10] = { 1, 9, 3, 5, 0, 8, 2, 4, 6, 7 };
	for (int i = 0; i < 10; i++){
		queue.Append(init[i]);
	}
	queue.Print();

	queue.Delete();

	queue.Print();

	system("pause");
	system("cls");

	PriorityQueue<SpecialData, SpecialCmp> spe_queue;
	int init2[5][2] = { { 34, 2 }, { 64, 1 }, { 18, 3 }, { 24, 2 }, { 55, 4 } };
	SpecialData data[5];
	for (int i = 0; i < 5; i++){
		data[i].m_npir = init2[i][1];
		data[i].m_ntenor = init2[i][0];
	}
	for (int i = 0; i < 5; i++){
		spe_queue.Append(data[i]);
	}
	spe_queue.Print();

	cout << spe_queue.GetFront() << endl << endl;
	spe_queue.Delete();
	//spe_queue.Print();

	cin.get();
	return 0;
}

运行效果如图1所示：

图1 运行效果