LeetCode(50):Pow(x,n)

public class Solution {
    public double myPow(double x, int n) {
        if(n<0){
            return 1.0/power(x,-n);
        }else{
            return power(x,n);
        }
    }
    public double power(double x,int n){
        if(n==0) return 1;
        double v = power(x,n/2);
        if(n%2==0){
            return v*v;
        }else{
            return v*v*x;
        }
    }
}