时间复杂度O(logn)，空间复杂度O(1)求一个数double x的n次幂

#include <iostream>

using namespace std;

double f(double x, int n);

int main(){
    
    cout<<f(3, 6)<<endl;
    return 0;
}

double f(double x, int n){
    double res = 1;
    while (n != 0) {
        if(n & 1) res *= x;
        x *= x;
        n = n >> 1;
    }
    return res;
}