In C++, the std::priority_queue is a container adapter class that provides a priority queue implementation. It is typically implemented as a max heap, where elements with higher priority are dequeued first.

Traditionally, the std::priority_queue is initialized using the constructor. However, with the introduction of uniform initialization syntax in C++11, we can now initialize it using the curly brace initializer syntax.

Here’s an example of how to initialize a std::priority_queue using uniform initialization in C++:

#include <queue>

int main() {
    std::priority_queue<int> pq {9, 4, 6, 2, 7};

    // Accessing the top element
    int topElement = pq.top();
    
    // Printing the elements in the priority queue
    while (!pq.empty()) {
        int element = pq.top();
        pq.pop();
        std::cout << element << " ";
    }
    std::cout << std::endl;

    return 0;
}

In the above code, we create a std::priority_queue called pq and initialize it using the uniform initialization syntax {9, 4, 6, 2, 7}. This inserts the numbers 9, 4, 6, 2, and 7 into the priority queue.

We can then access the top element of the priority queue using the top() function, which returns a reference to the highest priority element.

To print the elements in the priority queue, we use a loop that iterates until the queue is empty. In each iteration, we retrieve the top element, print it, and then remove it from the queue using the pop() function.

When executed, the output will be: 9 7 6 4 2, showing that the elements are dequeued in descending order, as expected from a max heap.

Using uniform initialization to initialize a std::priority_queue allows for a more concise and readable code. It is worth noting that the underlying container used by std::priority_queue is std::vector by default. If you want to use a different container, you can specify it as the second template argument.

For more information on std::priority_queue and its member functions, refer to the C++ documentation.

#cplusplus #datastructures