Priority Queue

The std::priority_queue is a reduced std::queue. It needs the header <queue>.

The difference to the std::queue is, that their biggest element is always at the top of the priority queue. std::priority_queue pri uses by default the comparison operator std::less. Similar to std::queue, pri.push(e) inserts a new element e into the priority queue. pri.pop() removes the first element of the pri, but does that with logarithmic complexity. With pri.top() you can reference the first element in the priority queue, which is the greatest one. The std::priority_queue knows its size, but didn’t support the comparison operator on their instances.

std::priority_queue

// priorityQueue.cpp 
...
#include <queue>
...
std::priority_queue<int> myPriorityQueue;

std::cout << myPriorityQueue.empty() << std::endl;   // true
std::cout << myPriorityQueue.size() << std::endl;    // 0

myPriorityQueue.push(3);
myPriorityQueue.push...