Stateful Lambda Counter

#include <iostream>
#include <string>
#include <functional>

class Ticker {
private:
    std::function<void()> callback;

public:
    void setCallback(std::function<void()> cb) {
        callback = cb;
    }

    void tick() {
        if (callback) callback();
    }
};

int main() {
    Ticker sys_tick;

    sys_tick.setCallback([count = 0]()mutable{
        ++count;
        std::cout << "Count: " << count << std::endl;
    });

    int N;
    if (!(std::cin >> N)) return 0;

    for (int i = 0; i < N; ++i) {
        std::string cmd;
        std::cin >> cmd;

        if (cmd == "TICK") {
            sys_tick.tick();
        }
    }
    return 0;
}

Solving Approach