Talk:Largest int from concatenated ints

From Rosetta Code

Negative integers[edit]

These programs look like they can't handle negative integers. I don't know how to concatenate two integers if the second one is negative; "4" "-5" => "4-5" is not an integer. Perhaps the task should specify positive integers? Or non-negative integers, if "0" is allowed? --Kernigh (talk) 00:38, 4 April 2013 (UTC)

Yep. I'm sloppy. I will fix this.Paddy3118 (talk) 05:51, 4 April 2013 (UTC)
Why can't zero be included?   That is, allow non-negative integers.   The programs (I think) won't barf if zero would be included in the list.   -- Gerard Schildberger (talk) 23:28, 7 April 2016 (UTC)
Well there is no need to wonder what a number with leading zeros is. Some conventions say ignore leading zeros on an int; others might treat it as signifying that the int should be considered as written in anther base, ... It's peripheral to the task, I guess you could state it as an extension to the task and how these leading zeroes are interpreted by your program, but you should have a first version that fits the task I would think. --Paddy3118 (talk) 19:00, 11 April 2016 (UTC)


Paddy3118, please clarify whether the list may or may not include duplicates. --Nigel Galloway (talk) 11:02, 4 April 2013 (UTC) PS where have the edit buttons gone?

Hi Nigel. Duplicates are not excluded. P.S. I assumed that the edit buttons were a (short term) casualty of the MW upgrade. Paddy3118 (talk) 16:09, 4 April 2013 (UTC)
The Haskell entry that uses cycle goes in infinite loop if you feed it with numbers like 10 and 1010.-bearophile (talk)

On "Python: Compare repeated string method" Second entry for Python 2.6[edit]

Hi Spoon, Is it the case that the first entry does not work on Python 2.6:

def maxnum(x):
maxlen = len(str(max(x)))
return ''.join(sorted((str(n) for n in x), reverse=True,
key=lambda i: i*(maxlen // len(i) + 1)))

The second version seems to be quite complex - using Fractions and logs, and although I do not have a version of Python 2.6 to hand, I cannot think of what of the above would break 2.6?

Here's your second version:

from fractions import Fraction
from math import log10
def maxnum(x):
return ''.join(str(n) for n in sorted(x, reverse=True,
key=lambda i: Fraction(i, 10**(int(log10(i))+1)-1)))

(P.S. thanks for catching my maxnumx errors)! --Paddy3118 (talk) 06:19, 6 April 2013 (UTC)

The first one under "repeated string" is infact incorrect. Try the array [212, 21221] and compare the result with other methods. You need to repeat each i to a length above maxlen + len(i). --Ledrug (talk) 08:17, 6 April 2013 (UTC)
Thanks Ledrug. I'll fix it. --Paddy3118 (talk) 11:37, 6 April 2013 (UTC)
Not at all. I was just expression that the second one requires Python 2.6+, since that's when the fractions module was added. I was not making any statement about the first version. --Spoon! (talk) 02:29, 7 April 2013 (UTC)