Bulb Switcher II — C++

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

class Solution {
public:
    int flipLights(int n, int m) {
        if (m == 0)           return 1;
        if (n == 1)           return 2;
        if (m == 1 && n == 2) return 3;
        if (m == 1 || n == 2) return 4;
        if (m == 2)           return 7;
        return 8;
    }
};