def fib(n):
if n == 1 or n == 2:
return 1
return fib(n-1) + fib(n-2)
for i in range(5):
print(fib(i))
I want to print first 5 result of Fibonacci sequence only to get
RecursionError: maximum recursion depth exceeded in comparison
I think there is an exit of every positive n and print(fib(4)), print(fib(20)) and print(fib(100)) works perfectly.
What's wrong with my code?
range(5) starts at 0 and since you are not checking for 0 in your function, the recursion never ends.
As a sidenote, you are not calculating the fibonacci sequence correctly, you should add up
fib(n-1) + fib(n-2)
Try this:
def fib(n):
if n <= 2:
return n
return fib(n-1) + fib(n-2)
A generally better approach at calculating the n-th fibonacci number is to use a loop, since you end up calculating the same values over and over again if you use recursion. Using a loop you can do it like this:
def fibonacci(n):
if n < 2:
return 1
a = 1
fib = 1
for i in range(n-2):
a, fib = fib, a + fib
return fib
if n < 2: and return n (fib(0) needs to be 0, if fib(1) and fib(2) are both 1, since we know that fib(n -2) == fib(n) - fib(n - 1) . Of course, that potentially leaves fib(-1) at the wrong value, but, you know...
n >= 0 , but yeah, for our purposes I think we can assume that n is not negative.there is an exit of every positive n.
Yes, there is. But how about fib(0)?
Try print(list(range(5)))
