C++ priority_queue - top() Function
The C++ priority_queue::top function returns a reference to the top element of the priority_queue. priority_queue is similar to a heap, where elements can be inserted in any order and max heap element is retrieved first. Hence, The first element of the priority_queue will be the max heap element.
Syntax
const value_type& top() const;
const_reference top() const;
Parameters
No parameter is required.
Return Value
A reference to the top element in the priority_queue.
Time Complexity
Constant i.e, Θ(1).
Example:
In the example below, the priority_queue::top function is used to access the top element of the priority_queue called pqueue.
#include <iostream> #include <queue> using namespace std; int main (){ priority_queue<int> pqueue; //add new elements in the priority_queue pqueue.push(100); pqueue.push(80); pqueue.push(990); pqueue.push(85); pqueue.push(10); cout<<"The top element of pqueue is: "; cout<<pqueue.top(); cout<<"\n\nDelete the top element of the pqueue.\n"; pqueue.pop(); cout<<"Now, The top element of pqueue is: "; cout<<pqueue.top(); return 0; }
The output of the above code will be:
The top element of pqueue is: 990 Delete the top element of the pqueue. Now, The top element of pqueue is: 100
❮ C++ <queue> Library