剑指Offer 数值的整数次方

class Solution {
public:
    double Power(double base, int exponent) {
        double sum = 1;
        if(base == 0)
            return 0;
        if(exponent == 0)
            return 1;
        int flag = 1;
        if(exponent < 0){
            flag = 0;
            exponent = -exponent;
        }
        for(int i = 1; i <= exponent; i++){
            sum = sum * base;
        }
        if(flag == 0)
            sum = 1/sum;
        return sum;
    }
};

这个就是要考虑下当exponent <= 0的情况，其他的不难。