State Machine with Enums

#include <iostream>
#include <string>
using namespace std;

enum class State { Idle, Busy, Error };

const char* toString(State s) {
    switch (s) {
        case State::Idle:  return "Idle";
        case State::Busy:  return "Busy";
        case State::Error: return "Error";
    }
    return "";
}

int main() {
    int n;
    cin >> n;

    State state = State::Idle;

    for (int i = 0; i < n; i++) {
        string cmd;
        cin >> cmd;

        if (state == State::Error) {
            continue; 
        }

        if(cmd == "start"){
            if(state == State::Idle){
                state = State::Busy;
            }
        }else if(cmd == "done"){
            if(state == State::Busy){
                state = State::Idle;
            }
        }else if(cmd == "fail"){
            if(state == State::Busy){
                state = State::Error;
            }
        }
        // implement transition logic to update state
    }

    cout << toString(state);
    return 0;
}

Solving Approach