pow_r

gistfile1.cpp

int64_t pow_r(int64_t a, int64_t b)
{
    if (b == 0)
        return 1;

    if (b == 1)
        return a;

    int64_t res = pow_r(a, b/2);
    res *= res;

    if (b % 2)
        res *= a;

    return res;
}