1 Introduction
priority_queue (priority queue) is a container adapter, the first element of the queue must be the highest priority in the queue ; the time complexity of inserting and extracting elements is logarithmic, providing a constant time search for the largest (by default) element .
priority_queue is a wrapper for vector;
header files and definitions
#include <queue>
template<
class T,
class Container = std::vector<T>,
class Compare = std::less<typename Container::value_type>
> class priority_queue;
2. Initialization
priority_queue does not support direct initialization, you can use copy initialization
example
int main(int argc, char* argv[])
{
std::priority_queue<int32_t> pri_que;
pri_que.emplace(12);
pri_que.emplace(22);
pri_que.emplace(32);
pri_que.push(28);
pri_que.push(18);
std::priority_queue<int32_t> pri_que1 = pri_que;
return 0;
}
3. use
| method | illustrate |
|---|---|
| operator= | assignment operation |
| top() | Returns the head element of the queue without deleting it |
| empty() | Determine whether priority_queue is empty |
| size() | Returns the size of priority_queue |
| push() | insert element |
| place() | Inserting elements is more efficient than push |
| pop() | Delete priority_queue queue head element |
| swap() | Swap the elements of two priority_queues |
example
/*
* @brief: priority_queue
* @compile: g++ -g priority_queue_main.cc -o d -std=c++11
* @author: your name
* @date: 2023/04/03
* @lastEditorDate:
*/
#include <iostream>
#include <queue>
#include <string>
#include <functional>
void printEnd(int32_t n){
for(size_t i =0; i<n;i++) std::cout<<std::endl;}
std::function<void(int32_t)> e = printEnd;
int main(int argc, char* argv[])
{
//operator= swap
//1.元素的插入，内部会进行排序
std::priority_queue<int32_t> pri_que;
pri_que.emplace(12);
pri_que.emplace(22);
pri_que.emplace(32);
pri_que.push(28);
pri_que.push(18);
std::priority_queue<int32_t> pri_que1 = pri_que;
std::cout<<"[pri_que value]";e(1);
//元素删除，删除队列首元素
for(;!pri_que.empty();pri_que.pop())
{
std::cout<<pri_que.top()<<" ";
}
e(2);
//2.队列的大小
pri_que = pri_que1;
std::cout<<"size value is: "<<pri_que.size();e(1);
//3.swap
std::priority_queue<int32_t> pri_que3;
pri_que3.swap(pri_que);
if(pri_que.empty())
{
std::cout<<"empty";
}
else{
std::cout<<"not empty";
}
e(1);
return 0;
}
output
[pri_que value]
32 28 22 18 12
size value is: 5
empty