1class Solution {2    public int lengthOfLongestSubstring(String s) {3        Map<Character, Integer> last = new HashMap<>();4        int left = 0, best = 0;5        for (int right = 0; right < s.length(); right++) {6            char c = s.charAt(right);7            left = Math.max(left, last.getOrDefault(c, -1) + 1);8            last.put(c, right);9            best = Math.max(best, right - left + 1);10        }11        return best;12    }13}