Quebrando Referências Circulares com Weak Pointers

              
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#include <iostream>
#include <memory>

class Node {
public:
    Node() { std::cout << "Node constructed." << std::endl; }
    ~Node() { std::cout << "Node destructed." << std::endl; }

    // A weak pointer to the next element prevents circular ownership.
    std::weak_ptr<Node> next;
};

int main() 
{
    // Creating three Node objects.
    std::shared_ptr<Node> node1 = std::make_shared<Node>();
    std::shared_ptr<Node> node2 = std::make_shared<Node>();
    std::shared_ptr<Node> node3 = std::make_shared<Node>();

    // Creating a list where the last node's next is a weak pointer
    node1->next = node2;
    node2->next = node3;
    node3->next = node1;
    // Now when node1, node2, and node3 go out of scope, their destructors will be called
}