50

class Solution {
public:
    double myPow(double x, int n) {
        double res = 1.0;
        while(n){
            if(n&1) {
                if(n > 0)
                    res = res*x;
                else
                    res /= x;
            }
            x = x*x;
            n /= 2;
        }
        return res;
    }
};