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一、优先队的使用：
二、基本数据类型：
priority_queue<int> q;//默认是从大到小
priority_queue<int, vector<int> ,less<int> >q;//从大到小排序
priority_queue<int, vector<int>, greater<int> >q;//从小到大排序
三、自定义类型:
第1种：
struct Node
{
char data;
int weight;
Node(char _data, int _weight)
{
data = _data;
weight = _weight;
}
};
(1)weight大的优先级高 :
struct cmp1
{
bool operator () (const Node &a, const Node &b)
{
return a.weight < b.weight;
}
};
构造优先队列：
priority_queue< Node, vector<Node>, cmp1> q1;
(2)weight小的优先级高
struct cmp2
{
bool operator()(const Node &a, const Node &b)
{
return a.weight > b.weight;
}
};
构造优先队列：
priority_queue<Node,vector<Node>,cmp2> q2;
第2种：
重载 < 运算符
(1)weight大的优先
struct Node2
{
char data;
int weight;
Node2(char _data, int _weight)
{
data = _data;
weight = _weight;
}
friend bool operator < (const Node2 &a,const Node2 &b)
{
return a.weight < b.weight;
}
};
构造优先队列：
priority_queue<Node2> q3;
（2)weight小的优先
struct Node3
{
char data;
int weight;
Node3(char _data, int _weight)
{
data = _data;
weight = _weight;
}
friend bool operator < (const Node3 &a,const Node3 &b)
{
return a.weight > b.weight;
}
};
构造优先队列：
priority_queue<Node3> q4;
test代码：
#include<iostream>
#include<vector>
#include<queue>
using namespace std;
struct Node
{
char data;
int weight;
Node(char _data, int _weight)
{
data = _data;
weight = _weight;
}
};
struct cmp1
{
bool operator () (const Node &a, const Node &b)
{
return a.weight < b.weight; //大的优先级高
}
};
struct cmp2
{
bool operator()(const Node &a, const Node &b)
{
return a.weight > b.weight; //小的优先级高
}
};
bool cmp(const Node &a,const Node &b)
{
return a.weight > b.weight;
}
struct Node2
{
char data;
int weight;
Node2(char _data, int _weight)
{
data = _data;
weight = _weight;
}
friend bool operator < (const Node2 &a,const Node2 &b)
{
return a.weight < b.weight;
}
};
struct Node3
{
char data;
int weight;
Node3(char _data, int _weight)
{
data = _data;
weight = _weight;
}
friend bool operator < (const Node3 &a,const Node3 &b)
{
return a.weight > b.weight;
}
};
int main()
{
string values = "ABCDEF";
vector<int> weights = {
1,2,3,4,5,6};
priority_queue< Node, vector<Node>, cmp1> q1;
for(int i = 0; i < values.length(); i++)
{
Node newNode(values[i],weights[i]);
q1.push(newNode);
}
cout<<"优先队列q1的第一个元素是: "<<q1.top().data<<endl;
priority_queue<Node,vector<Node>,cmp2> q2;
for(int i = 0; i < values.length(); i++)
{
Node newNode(values[i],weights[i]);
q2.push(newNode);
}
cout<<"优先队列q2的第一个元素是: "<<q2.top().data<<endl;
priority_queue<Node2> q3;
for(int i = 0; i < values.length(); i++)
{
Node2 newNode(values[i],weights[i]);
q3.push(newNode);
}
cout<<"优先队列q3的第一个元素是: "<<q3.top().data<<endl;
priority_queue<Node3> q4;
for(int i = 0; i < values.length(); i++)
{
Node3 newNode(values[i],weights[i]);
q4.push(newNode);
}
cout<<"优先队列q4的第一个元素是: "<<q4.top().data<<endl;
}
运行截图:
更新:
priority_queue< pair<double,int>,
vector<pair<double,int> >,
greater<pair<double,int> > > pq; //first小的优先
priority_queue< pair<double,int>,
vector<pair<double,int> >,
less<pair<double,int> > > pq; //first大的优先
first小的优先
class cmp
{
public:
bool operator()(pair<double,int> x, pair<double,int> y)
{
return x.first > y.first;
}
};
first大的优先
class cmp
{
public:
bool operator()(pair<double,int> x, pair<double,int> y)
{
return x.first < y.first;
}
};
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