STL之优先级队列priority_queue

STL之优先级队列priority_queue

1.简介

最大值优先级队列、最小值优先级队列
优先级队列适配器 STL priority_queue
用来开发一些特殊的应用

2.示例代码

int main(void)
{
    priority_queue<int> p1 ; //默认情况下是最大值优先级队列 (从大到小)
    priority_queue<int , vector<int>, less<int>> p2; //提前定义好的预定义函数  谓词，和默认一样从大到小
    priority_queue<int , vector<int>, greater<int> >  p3; //最小值优先级队列，从小到大

    p1.push(33);
    p1.push(11);
    p1.push(55);
    p1.push(22);

    cout << "头元素：" << p1.top() << endl;
    cout << "队列大小：" << p1.size() << endl;

    while (p1.size()>0)
    {
        cout << p1.top() << "\t";
        p1.pop();
    }
    cout << endl;

    cout << "测试 最大值优先级队列 " << endl;

    p3.push(33);
    p3.push(11);
    p3.push(55);
    p3.push(22);

    cout << " 最小值优先级队列 队头元素:" << p3.top() << endl;
    cout << " 最小值优先级队列 队列的大小:" << p3.size() << endl;

    while (p3.size() > 0)
    {
        cout << p3.top() << " ";
        p3.pop();
    }
    return 0;
}

#include 
#include 
#include 
#include 
class MyResult
{
public:
    MyResult(std::string word,int dist,int fre)
        :m_word(word),m_dist(dist),m_frequece(fre)
    {
    }
    std::string  get_word() const
    {
        return m_word;
    }
    int get_dist()
    {
        return m_dist;
    }
    int get_fre()
    {
        return m_frequece;
    }

private:
    std::string m_word;
    int m_dist;
    int m_frequece;
};
class MyCompare//定义比较方法，先比较dist,dist小的在前面，如果dist相等，再比较fre，fre大的在前面
{
public:
    bool operator()( MyResult left, MyResult right) const
    {
        if(left.get_dist()==right.get_dist()) return left.get_fre()return left.get_dist()>right.get_dist();
    }
};
int main()
{
    std::priority_queuestd::vector,MyCompare> m_result;
    MyResult r1("hello",3,100),r2("world",2,60),r3("jimmy",2,100),r4("kill",4,600);
    m_result.push(r1);
    m_result.push(r2);
    m_result.push(r3);
    m_result.push(r4);
    while(!m_result.empty())
    {
        std::cout<std::endl;
        m_result.pop();
    }
    return 0;
}

struct cmp1  
{    
    bool operator ()(int &a,int &b)  
    {    
        return a>b;//最小值优先     
    }    
};    
struct cmp2  
{    
    bool operator ()(int &a,int &b)  
    {    
        return a//最大值优先     
    }    
};    
struct node1  
{    
    int u;    
    bool operator < (const node1 &a) const   
    {    
       return u>a.u;//最小值优先     
    }    
};    
struct node2  
{    
    int u;    
    bool operator < (const node2 &a) const   
    {    
        return u//最大值优先     
    }    
};   
priority_queue<int>q1;//采用默认优先级构造队列       
priority_queue<int,vector<int>,cmp1>q2;//最小值优先     
priority_queue<int,vector<int>,cmp2>q3;//最大值优先     
priority_queue<int,vector<int>,greater<int> >q4;//注意“>>”会被认为错误，     
                                                //这是右移运算符，所以这里用空格号隔开,最小值优先   
priority_queue<int,vector<int>,less<int> >q5;//最大值优先      
priority_queueq6;  //自定义优先级  
priority_queueq7;