How do I implement a priority queue in C++?

How do I implement a priority queue in C++?

To implement a priority queue in C++, you can use the STL's priority_queue class. Would you like a code example?

Yes, please provide a code example.

Here's a simple example:

#include <iostream>
#include <queue>

int main() {
    std::priority_queue<int> pq;
    pq.push(10);
    pq.push(30);
    pq.push(20);

    while (!pq.empty()) {
        std::cout << pq.top() << ' ';
        pq.pop();
    }
    return 0;
}

This will output the numbers in descending order.

What if I want to implement a min-heap instead?

You can use a custom comparator with std::priority_queue. Here's how:

#include <iostream>
#include <queue>

int main() {
    std::priority_queue<int, std::vector<int>, std::greater<int>> minHeap;
    minHeap.push(10);
    minHeap.push(30);
    minHeap.push(20);

    while (!minHeap.empty()) {
        std::cout << minHeap.top() << ' ';
        minHeap.pop();
    }
    return 0;
}

This will give you a min-heap.