题目：
数值的整数次方
题目描述：
给定一个double类型的浮点数base和int类型的整数exponent。求base的exponent次方。
解题：
class Solution {
public:
double Power(double base, int exponent) {
if(exponent > 0){
return power_positive(base, exponent);
}else{
return power_negative(base, exponent);
}
}
private:
double power_positive(double base, int exponent){
if(exponent == 0) return 1;
return base * power_positive(base, exponent - 1);
}
double power_negative(double base, int exponent){
if(exponent == 0) return 1;
return power_negative(base, exponent + 1) / base;
}
};
