293. Flip Game

293. Flip Game

for (int i = 0; i < s.length() - 1; i++) would generate run time error when test case is s = "". Because s.length() is unsigned int

vector<string> generatePossibleNextMoves(string s) {
        vector<string> res;
        for (int i = 0; i < (int)s.length() - 1; i++) {
            if (s[i] == '+' && s[i + 1] == '+') {
                s[i] = '-';
                s[i + 1] = '-';
                res.push_back(s);
                s[i] = '+';
                s[i + 1] = '+';
            }
        }
        return res;
    }