C++ 解法, 执行用时: 2ms, 内存消耗: 404KB, 提交时间: 2021-05-31

class Solution {
public:
    double Power(double base, int exponent) {
        double result = base;
        bool flag = false;
        if(!exponent) return 1;
        if(!base) return 0;
        if(exponent < 0) {
            exponent = -exponent;
            flag = true;
        }
        while(exponent-- > 1)
            result *= base;
        if(flag) result = 1/result;
        
        return result;
    }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 464KB, 提交时间: 2021-07-13

class Solution {
public:
    double Power(double base, int exponent) {
        if(exponent==0){
            return 1;
        }
        if(exponent<0){
            base=1/base;
            exponent=-1*exponent;
        }
        return (exponent%2==0)?Power(base*base, exponent/2):base*Power(base*base, exponent/2);
        }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 468KB, 提交时间: 2021-07-17

class Solution {
public:
    double Power(double base, int exponent) {
        if(base==0||base==1) return base;
        long a=exponent;
        if(a<0){
            base=1/base;
            a=-a;
        }
        double ans=1;
        while(a){
            if(a&1) ans*=base;
            base*=base;
            a>>=1;
        }
        return ans;
    }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 476KB, 提交时间: 2021-04-25

class Solution {
public:
    double mypow(double base, int exponent){
        double res = 1.0;
        while(exponent){
            if(exponent & 1){
                res *= base;
            }
            base *= base;
            exponent >>= 1;
        }
        return res;
    }
    double Power(double base, int exponent) {
        if(base == 0){
            return 0;
        }
        if(exponent==0){
            return 1;
        }
        if(exponent < 0)
        {
            base = 1.0 / base;
            exponent = -exponent;
        }
        return mypow(base, exponent);
    }
};

C++ 解法, 执行用时: 2ms, 内存消耗: 484KB, 提交时间: 2021-05-03

class Solution {
public:
    double Power(double base, int exponent)
    {
        double res = 1.0;
        if(exponent<0)base = 1.0/base,exponent*=-1;
        while(exponent)
        {
            if(exponent&1)res = res*base;
            base*= base;
            exponent>>=1;
        }
        return res;
    }
};