# @param {String} s
# @return {Integer}
def length_of_longest_substring(s)
    result = []
    (0..s.length-1).each do |i|
        result << s[i]
        (i..s.length-1).each do |j|
            result << s[i..j] if j > i && s[i..j].split('') == s[i..j].split('').uniq
        end
    end
    longest = result.sort_by {|sub| sub.length}.last
    longest.length
end