Python ValueError for code that calculates correct results

Question

Problem Statement

Given an integer n, find two integers a and b such that,

#a >= 0 and b >= 0
#a + b = n
#DigitSum(a) + Digitsum(b) is maximum of all possibilities

def solve(n): 

    len_of_n = len(str(n))
    len_of_n-=1
    a = '9'
    a = (a*len_of_n)
    #print(a)
    b = (int(n) - int(a) )  # This is the line where it points to error.
    #print(b)

    digits_of_a = []
    digits_of_b = []
    for i in str(a)[::-1]:
         digits_of_a.append(int(i))   
    for i in str(b)[::-1]:
         digits_of_b.append(int(i))

    return (sum(digits_of_a) + sum(digits_of_b))

The code actually reports correct answers on test cases on 'attempts' on codewars.com but fails final submission. It exits with error code 1. It says ValueError: invalid literal for int() with base 10: ''

I have read this other thread on this and understand that error is due to trying to convert a space character to an integer. Can't figure why would that statement get space charater. Both of them are int representations of string...?

What are the values of n and a when it hits the error? It And what are you passing into the function? The most likely thing, I think, is that the string n is unable to be casted to an int, either because it's an empty string or because it has non-digit characters in it. — Green Cloak Guy
– Green Cloak Guy, Commented Nov 24, 2018 at 7:19
n is an integar passed to the func. a is constructed on the fly based on total 'digits' in the n. Error suggests it's due to empty string. But I cannot figure why/how can I have empty string with valid int value n passed to the def. — Jigish Parikh
– Jigish Parikh, Commented Nov 24, 2018 at 7:29
@TobiasWilfert Had changed as part of trial and error.. Originally I just had (n - int(a)) I am not sure what values are passed by the test engine. The test cases on codewars shows all 8 assertions passed but then also shows this error. So it deems my code inadmissible. Snapshot below. — Jigish Parikh
– Jigish Parikh, Commented Nov 24, 2018 at 7:33

Tobias · Accepted Answer · 2018-11-24 07:32:42Z

2

When you pass a single digit int to the function you get this error because len_of_n = len(str(n)) will be equal to 1 and len_of_n-=1 will be equal to 0. 0 * '9' will give you an empty string which can not be converted to an int. Thus giving you the error

invalid literal for int() with base 10: ' '

answered Nov 24, 2018 at 7:32

Tobias

9693 gold badges14 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Jigish Parikh Over a year ago

Bingo! Makes sense. Let me edit and give one more go!

Tobias Over a year ago

@JigishParikh you will probably need to make an extra case if n is only 1 digit.

Collectives™ on Stack Overflow

Python ValueError for code that calculates correct results

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related