50. Pow(x, n) (INT; Divide-and-Conquer)

class Solution {
public:
    double pow(double x, int n) {
        if(n == 0) return 1;
        return divideConquer(x,n);
    }
    double divideConquer(double x, int n)
    {
        double result;
        if(n==1) return x;
        if(n == -1) return 1/x;
        if(n%2 == 0)
        {
            result = divideConquer(x, n/2);
            result = result * result;
        }
        else
        {
            result = divideConquer(x, n/2);
            if(n>0)   result = result * result * x;
            else result = result * result / x;
        }
        return result;
    }
};