Implement pow(x, n).
public class Solution {
public double pow(double x, int n) {
if(n>0) return powInt(x,n);
else return 1/powInt(x,-n);
}
private double powInt(double x, int n){
if (n == 0)
return 1;
if (n == 1)
return x;
double p = pow(x, n / 2);
if (n % 2 == 0) {
return p * p;
}else{
return p*p*x;
}
}
}