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#include <iostream>
#include <memory>
#include <string>
#include <vector>

struct Resource {
    std::string name;
    explicit Resource(std::string n) : name(std::move(n)) {
        std::cout << "Resource '" << name << "' acquired
";
    }
    ~Resource() {
        std::cout << "Resource '" << name << "' released
";
    }
};

void useResource(std::shared_ptr<Resource> r) {
    std::cout << "Using: " << r->name
              << " (use_count=" << r.use_count() << ")
";
}

int main() {
    // make_shared: single allocation for object + control block
    auto r1 = std::make_shared<Resource>("Database");
    std::cout << "r1 use_count = " << r1.use_count() << "
";  // 1

{
        auto r2 = r1;   // shared ownership — count becomes 2
        std::cout << "r1 use_count = " << r1.use_count() << "
";  // 2
        useResource(r2);   // count temporarily 3 inside function
        std::cout << "r1 use_count = " << r1.use_count() << "
";  // 2
    }
    // r2 out of scope — count back to 1
    std::cout << "r1 use_count = " << r1.use_count() << "
";  // 1

// Vector of shared_ptrs — all share the same Resource
    std::vector<std::shared_ptr<Resource>> holders;
    holders.push_back(r1);
    holders.push_back(r1);
    std::cout << "use_count with vector = " << r1.use_count() << "
";  // 3

holders.clear();   // removes two shares
    std::cout << "use_count after clear = " << r1.use_count() << "
"; // 1

return 0;   // Resource released here
}