public int lengthOfLongestSubstring(String s) {

        int length = 0;

        char[] chars = s.toCharArray();

        Map<Character, Set<Character>> map = new LinkedHashMap<>();

        for (int i = 0; i < chars.length; i++) {

            char c = chars[i];

            Set<Character> set = new HashSet<>();

            for (int j = i; j < chars.length; j++) {

                char cj = chars[j];

                if (!set.contains(cj)) {

                    set.add(cj);

                } else {

                    break;

                }

            }

            if (map.get(c) == null || map.get(c).size() < set.size()) {

                map.put(c, set);

            }

        }

        for (Map.Entry<Character, Set<Character>> entry : map.entrySet()) {

            int lengthTmp = entry.getValue().size();

            if (lengthTmp >= length) {

                length = lengthTmp;

            }

        }

        return length;

    }