class Solution {
public:
    double Power(double base, int exponent) {
        if(base == 0)return 0;
        if(exponent == 0 )return 1;
        double ans = 1;
        int cur = base ;
        int flag = 0 ;
        if(exponent<0){
            flag = 1 ;//负数标记
            exponent = -exponent ;
        }
        //快速幂运算
        while(exponent>0){
            if((exponent&1)==1){
                ans*=cur;
            }
            cur*=cur; exponent = exponent>>1;
        }
        
        if(flag)ans = 1/ans ;
        return ans ;
    }
};