Python Recursive Function For Collatz Conjecture

I have written the following recursive program to show the number of steps a number goes through in Collatz Conjecture: def cycle_length(n): count = 0 if n == 1: re

Solution 1:

When n is 1, you need to increment count by 1 before returning it.

def cycle_length(n):
    count =0if n == 1:
        return count + 1# or simply return 1
    ...

But I think your code is syntactically correct if you do not choose to count the zeroth step.

See http://oeis.org/A070165.

Solution 2:

When you are making count=1, you should not do count+= in the later if, else if statements. Also, it seems to me that you earlier answer already correct. However, if you want to add 1 to it (i.e. counting the step when 1 occurs), just do the following:

defcycle_length(n):
    count = 1if n == 1:
        return count
    if n%2 == 0:
        count = (cycle_length(int(n/2)) +1)
    elif n%2 != 0:
        count = (cycle_length(int(3*n+1)) + 1)
    return count

Solution 3:

the Collatz sequence always start in the given number, therefore your base case should be return 1

that being said, you can also calculate it using iteration as python is not very fond of recursion, for example your code cannot calculate 9780657631 or 75128138247 without getting a recursion error

here is the iterative version

def collatz_length(n):
    if n<1:
        raise ValueError
    count =1while n != 1:
        if n%2 == 0:
            n = n//2else:
            n = 3*n+1
        count += 1return count