non_repeated_char_2.rb

def first_nonrepeated_char( string )
  chars = string.gsub(" ", "").chars

  chars.each_with_index do |ch, index|
    # Skip characters that we have already marked as repeats.
    next if ch.empty?
    
    match = false
    
    # Compare each character with the characters that follow it.
    ((index+1)..(chars.length - 1)).each do |index2 |

      # If we find a match, set the matching character to "" so 
      # we don't have to check it again
      if ch == chars[index2]
        match = true
        chars[ index2 ] = ""
      end
    end

    # Return the character and end unless it had a match
    return ch unless match
  end
  
  # return nil to indicate that every character had a repeat
  return nil
end