Traffic Signal Color — C++

// Time:  O(1)
// Space: O(1)

// simulation
class Solution {
public:
    string trafficSignal(int timer) {
        if (timer == 0) {
            return "Green";
        } else if (timer == 30) {
            return "Orange";
        } else if (30 < timer && timer <= 90) {
            return "Red";
        }
        return "Invalid";
    }
};