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