Configurable Math Engine

#include <iostream>
#include <string>

using MathOp = int (*)(int, int);

int add(int a, int b) { return a + b; }
int multiply(int a, int b) { return a * b; }

class Calculator {
private:
    MathOp current_op = add;
    
public:
    
    void setMode(MathOp op){
        current_op = op;
    }

    void compute(int a, int b) {
        std::cout << "Result: " << current_op(a,b) << std::endl;
    }
};

int main() {
    Calculator calc;
    int N;
    if (!(std::cin >> N)) return 0;

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

        if (cmd == "MODE_ADD") {
             calc.setMode(add);
        } else if (cmd == "MODE_MUL") {
             calc.setMode(multiply);
        } else if (cmd == "CALC") {
            int a, b;
            std::cin >> a >> b;
            calc.compute(a, b);
        }
    }
    return 0;
}

Solving Approach