[Leetcode] Pow(x, n)

 1 class Solution {
 2 public:
 3     double pow(double x, int n) {
 4         if (n == 0) return 1;
 5         if (n < 0) return 1 / (pow(x, -(n + 1)) * x);
 6         double e = pow(x, n / 2);
 7         if (n % 2 == 0) {
 8             return e * e;;
 9         } else {
10             return x * e * e;
11         }
12     }
13 };