from operator import mul
from functools import reduce


def factorial1(n):
    if n < 0:
        raise Exception("Cannot determine factorial for n < 0")
    if n <= 1:
        return 1
    else:
        return factorial1(n - 1) * n


def factorial2(n):
    if n < 0:
        raise Exception("Cannot determine factorial for n < 0")
    else:
        result = 1
        for i in range(2, n + 1):
            result *= i
        return result


def factorial3(n):
    if n < 0:
        raise Exception("Cannot determine factorial for n < 0")
    return reduce(mul, range(1, n + 1), 1)


def fibonacci1(n):
    if n <= 0:
        return 0
    elif n == 1:
        return 1
    elif n == 2:
        return 1
    else:
        return fibonacci1(n - 1) + fibonacci1(n - 2)


def fibonacci2(n):
    a = 0
    b = 1
    c = 1
    if n < 0:
        raise Exception("Cannot determine fibonacci for n < 0")
    elif n == 0:
        return a
    elif n == 1:
        return b
    elif n == 2:
        return c
    else:
        for i in range(2, n):
            d = b + c
            b = c
            c = d
        return c


def fibonacci3(n, x=[0, 1]):
    for i in range(abs(n)-1):
        x = [x[1], sum(x)]
    return x[1]*pow(-1, abs(n) - 1) if n < 0 else x[1] if n else 0


def return_correct_or_throw(val1, val2, val3):
    if val1 == val2:
        return val1
    if val1 == val3:
        return val3
    if val2 == val3:
        return val2
    raise Exception("Cannot determine correct value!")


if __name__ == "__main__":
    input = -1
    try:
        res = return_correct_or_throw(factorial1(input), factorial2(input), factorial3(input))
        print("Correct value for factorial({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 0
    try:
        res = return_correct_or_throw(factorial1(input), factorial2(input), factorial3(input))
        print("Correct value for factorial({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 1
    try:
        res = return_correct_or_throw(factorial1(input), factorial2(input), factorial3(input))
        print("Correct value for factorial({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 2.5
    try:
        res = return_correct_or_throw(factorial1(input), factorial2(input), factorial3(input))
        print("Correct value for factorial({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 10000
    try:
        res = return_correct_or_throw(factorial1(input), factorial2(input), factorial3(input))
        print("Correct value for factorial({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))


    input = -1
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 0
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 1
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 2.5
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 5
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))

    input = 10000
    try:
        res = return_correct_or_throw(fibonacci1(input), fibonacci2(input), fibonacci3(input))
        print("Correct value for fibonacci({}) is {}".format(input, res))
    except Exception as e:
        print(str(e))