Interview Question : Trim multiple consecutive spaces from a string

Question

This is an interview question Looking for best optimal solution to trim multiple spaces from a string. This operation should be in-place operation.

input  =          


        

Answer 1

Functional variant in Haskell:

import Data.List (intercalate)

trimSpaces :: String -> String
trimSpaces =  intercalate " " . words

The algorithm the next:

1. breaks a string up into a list of words, which were delimited by white space
2. concatenate the list inserting one space between each element in list