Codewars kata training. Returns None

Question

Why this code return None? But print(sum_) in else, gives the correct answer

n = 942

def digital_root(n):
    n_str = str(n)
    result = []
    sum_ = 0
    for i in range(0, len(n_str), 1):
        result.append(int(n_str[i: i + 1]))

    for i in result:
        sum_ += i
    
    if len(str(sum_)) > 1:
        digital_root(sum_)

    else:
        return sum_

You want to learn [how to debug small programs](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/) and use an IDE on your machine, not just an online editor. — Thomas Weller, Jul 20 '23 at 08:10

Luff li · Answer 1 · 2023-07-20T08:31:26.410

0

Here when you are calling the function recursively it calculates the root correctly but it is not returning anything to the caller.

if len(str(sum_)) > 1:
     return  digital_root(sum_)

Please add the return statement and try.

edited Jul 20 '23 at 08:31

answered Jul 20 '23 at 08:13

Luff li

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score 0 · Answer 2 · answered Jul 20 '23 at 08:17

you lose return before the digital_root(sum_) digital_root(sum_) -> return digital_root(sum_)

def digital_root(n):
    n_str = str(n)
    result = []
    for i in range(0, len(n_str), 1):
        result.append(int(n_str[i: i + 1]))

    sum_ = sum(result)
    if len(str(sum_)) > 1:
        return digital_root(sum_)
    else:
        return sum_

Codewars kata training. Returns None

2 Answers2