数值的整数次方

class Solution {
public:
	double Power(double base, int exponent) {
		if(exponent == 0)
            return 1;
        if(base - 0.0 < 1e-9 && base - 0.0 > -1e-9)
            return 0.0;
        double result = base;
        //这里exponent != INT_MIN
        int n = abs(exponent);
        for(int i = 1; i < n; i++)
            result *= base;
        return (n / exponent) == 1 ? result : 1.0 / result;
	}
};