50. Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (i.e. xn).

class Solution {
    public double myPow(double x, int n) {
        if (n<0){
            x=1/x;
            n=-1*n;
        }
        return pow(x, n);
    }

    private double pow(double x, int n){
        if(n==0) return 1;
        double value = pow(x, n/2);
        if (n%2==0){
            return value*value;
        }else{
            return value*value*x;
        }
    }
}