Problem spec from CareerCup https://careercup.com/question?id=5092486548553728. Given two strings, return boolean True/False if they are only one edit apart. Edit can be insert/delete/update of only one character in the string. Eg. -True xyz,xz xyz,xyk xy,xyz -False xyz,xyz xyz,xzy x,xyz module Strings.OneLetter where` import Preludeimport qualified Data.Text as T` oneLetter :: T.Text -> T.Text -> Bool oneLetter s1 s2 | s1 == s2 = False | max_l > (min_l + 1) = False | max_l == min_l = diff_size == 1 | otherwise = diff_size == 0 where length_s1 = T.length s1 length_s2 = T.length s2 max_l = max length_s1 length_s2 min_l = min length_s1 length_s2 diff_size = length $ filter (\(a,b) -> a /= b) zipped zipped = T.zip s1 s2` So, I used Text instead of String, hoping I could take advantage of fusion. I have the following questions and my initial attempt to answer them. What is the time complexity of oneLetter 0(m+n) where m is the length of s1 and n is the length of s2 what is the space complexity of oneLetter? I'm thinking due to laziness it's O(1), only two Chars are in memory at any one time, or two Ints. But I'm hazy on why. If this is wrong, please articulate why. If I'm right, and my reasoning is wrong or incomplete, please say why. I don't think I can improve the time complexity. Am I right? Can the space complexity be improved? What if I changed from Text to String? I don't think the time complexity changes, but how does this change the space complexity?