| require 'set' | |
| def palindrome_permutation?(input_string) | |
| # create a set to track characters we've seen | |
| charSet = Set.new | |
| # iterate over each character by spitting into an array | |
| input_string.split('').each do |char| | |
| # remove from set if previously added | |
| if charSet.include? char | |
| charSet.delete(char) | |
| # add to set if not already present in set | |
| else | |
| charSet.add(char) | |
| end | |
| end | |
| # set should have 0 or 1 entry if is a palindrome | |
| charSet.length <= 1 | |
| end |