sword to offer 012

class  {
private:
    double QuickPower(double base, int exponent) {
        double res = 1.0;
        if(exponent < 0) {
            base = 1.0 / base;
            exponent = -exponent;
        }
        while(exponent) {
            if(exponent & 1) {
                res *= base;
            }
            base *= base;
            exponent >>= 1;
        }
        return res;
    }
public:
    double Power(double base, int exponent) {
        return QuickPower(base, exponent);
    }
};