劍指offer---數值的整數次方

class Solution {
public:
    //注意exponent有負數的情況
    double Power(double base, int exponent) {
    
        if(exponent==0)return 1;
        if(base==0) return 0;
        double res=1;
        for(int i=0;i<abs(exponent);i++)
            res=res*base;
       if(exponent>0)
            return res;
        else return 1/res;
    }
};