Quiz 8 (Fibonacci)

The task:

• Write a function that calculates returns the “nth” Fibonacci number where we define a function over the Fibonacci numbers mapping the naturals (starting with zero) to the Fibonacci series. So fibonacci(0) returns 0, fibonacci(1) returns 1, fibonacci(2) returns 1 and so on. Note that we are using the modern definition where the sequence starts with zero. You should try to implement this with two solutions: one with a loop and one with recursion. Which do you think is “better”, which looks more “elegant”, which is more “efficient”?

(Here´s a link to know what a fibonacci series looks like: https://en.wikipedia.org/wiki/Fibonacci_number)

So first let's go to the recursion solution, which in my opinion, is the easiest:

Here´s the code: 

def fib(x):

    if x==0:

        return 0

    elif x==1:

        return 1

    else:

        return fib(x-1)+fib(x-2)

x=int(input("Write a number:"))

print ("The fibonacci is:", fib(x))

Now let´s go to the Looping solution:

Here´s the code for the loop method:

def fib(x):

    if x==0:

        return 0

    if x==1:

        return 1

    a=0

    b=1

    for counter in range(x-1):

        c=a+b

        a=b

        b=c

    return c

x=int(input("Write a number:"))

print ("The fibonacci is:", fib(x))