Python求快速幂

#mod:最后结果要取的模
def fast_pow(base, n, mod):
    res = 1
    if base == 0:
    	return 0
    if n < 0:
        base, n = 1 / base, -n
    while n:
        if n & 1:
            res *= base % mod
        base *= base
        n >>= 1
    return res
if __name__ == '__main__':
     print(fast_pow(3, 4, 1000000))