STL Priority Queue for Structure or Class in C++

STL Priority Queue is the implementation of maxheap.

This is a C++ program of STL priority queue for structure.

Algorithm

Begin
   Define a structure of type student.
   Initialize variables in student structure.
   Define another structure of type comparemarks
   Overload the variables of student structure in comapremarks
   structure.
   Use priority queue with structure.
   Insert some elements in priority queue using student structure.
   While the queue is not empty do
      Print the elements.
End.

Example Code

 Live Demo

#include <iostream>
#include <queue>
using namespace std;
#define ROW 6
#define COL 3
struct student { //defining the student structure
   int roll,marks;
   student(int roll, int marks)
      : roll(roll), marks(marks)
   {
   }
};
struct comparemarks{ // defining the comparemarks structure
   bool operator()(student const& s1, student const& s2)
   //overloading the operators of the student structure
   {
      return s1.marks < s2.marks;
   }
};
int main()
{
   priority_queue<student, vector<student>, comparemarks> M;
   // using the priority queue. We have to use this type of syntax to use the priority queue.
   int a[ROW][COL] = {{15, 50}, {16, 60},
   {18,70}, {14, 80}, {12, 90}, {20, 100}};
   for (int i = 0; i < ROW; ++i) {
      M.push(student(a[i][0], a[i][1])); //inserting variables in the queue
   }
   cout<<"priority queue for structure ::"<<endl;
   while (!M.empty()) {
      student s = M.top();
      M.pop();
      cout << s.roll << " " << s.marks << "\n"; //printing the values
   }
   return 0;
}

Output

priority queue for structure ::
20 100
12 90
14 80
18 70
16 60
15 50