Pow(x, n)

class Solution {public:    double myPow(double x, int n)     {        if(n<0)        {            if(n==INT_MIN)                return pow(x,n+1)/x;            else            {                x=1/x;                n=-n;            }        }                return Helper(x,n);            }    double Helper(double x,int n)    {        if(n==0)            return 1;        double temp=Helper(x,n>>1);        if(n&1)            return temp*temp*x;        else            return temp*temp;    }};