How can I implement custom comparators in a C++ priority queue?

How can I implement custom comparators in a C++ priority queue?

You can implement custom comparators by defining a struct or a function that overloads the operator(). This comparator will dictate the order of elements in the priority queue.

Can you show me a code example of that?

Sure! Here's a simple example:

#include <queue>
#include <vector>
#include <iostream>

struct CustomComparator {
    bool operator()(int a, int b) {
        return a > b; // Min-heap
    }
};

int main() {
    std::priority_queue<int, std::vector<int>, CustomComparator> pq;
    pq.push(10);
    pq.push(5);
    pq.push(20);

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

This will create a min-heap priority queue.

What if I want a max-heap instead?

For a max-heap, you can simply change the comparison in the operator() to return a < b;. This will ensure that the largest element is at the top of the queue.

Thanks! Are there any other features I should know about priority queues?

Yes! You can also use different data types, manage custom objects, and even combine multiple comparators for complex sorting.