LeetCode Problem : Pow(x, n)

Problem

Implement pow(x, n).

Code

double pow_r(double x, int n) {
    if(n == 0)
        return 1.0;
    double ret = pow_r(x*x,n / 2);
    if(n % 2 == 1)
        ret *= x;
    return ret;
}
double pow(double x, int n) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
    int m = abs(n);
    double ret = pow_r(x,m);
    return ((n < 0) ? 1.0/ret : ret);
}