C++STL之priority_queue优先队列容器

特征：就是队列中最大元素总是在队首

*优先队列使用方法

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

int main()
{
priority_queue<int> pq;
pq.push(2);
pq.push(0);
pq.push(1);
pq.push(5);
cout<<pq.size()<<endl;

while(pq.empty() != true)
{
cout<<pq.top()<<" ";
pq.pop();
}
cout<<endl;

return 0;
}

*重载"<"操作符来定义优先级

如果优先队列的元素类型是结构体，可以通过在结构体中重载"<"操作符的方法来修改优先队列的优先性。

#include<iostream>
#include<string>
#include<queue>
using namespace std;

struct Info
{
string name;
float score;

bool operator < (const Info& a)const
{
//由小到大排序
return a.score < score;
}
};

int main()
{
priority_queue<Info> pq;
Info info;
info.name = "CaiCai";
info.score = 68.5;
pq.push(info);

info.name = "Zhejiang";
info.score = 90;
pq.push(info);

info.name = "Ningbo";
info.score = 78.2;
pq.push(info);

while(pq.empty() != true)
{
cout<<pq.top().name<<" : "<<pq.top().score<<endl;
pq.pop();
}
return 0;
}

*重载“（）”操作符来定义优先级

如果优先队列元素不是结构体类型，可以通过重载"()"操作符的方式来定义优先级，当然若元素是结构体类型，也可以通过重载"()"操作符的方式来定义优先级，而不是一定要在结构体内重载"<"操作符。

#include<iostream>
#include<vector>
#include<queue>
using namespace std;

struct cmp
{
bool operator () (const int& a, const int& b)
{
//由小到大
return a < b;
}
};

int main()
{
priority_queue<int, vector<int>, cmp> pq;
pq.push(2);
pq.push(0);
pq.push(1);
pq.push(5);
pq.push(10);
pq.push(23);
while(pq.empty() != true)
{
cout<<pq.top()<<" ";
pq.pop();
}
cout<<endl;

return 0;
}