Pow(x, n)

class Solution {
public:
    double myPow(double x, int n) {
        double ans=1.0;
        long long int nn=n;
        if(nn<0) nn=-1*nn;
        while(nn)
        {
            if(nn%2)
            {
                ans=ans*x;
                nn-=1;
            }
            else
            {
                x=x*x;
                nn/=2;
            }
            
        }
        if(n<0) ans=(double)1.0/(double) ans;
        return ans;
    }
};