class Solution {
    public int lengthOfLongestSubstring(String s) {

        Map<Character, Integer> map = new HashMap<>();

        int l = 0;
        int r = 0;
        int max = 0;
        char c ;
        //" "
        while(r < s.length()){
            c = s.charAt(r); //a
            if(map.containsKey(c) && map.get(c) >=  l){
                max = Math.max(r-l, max); // 3
                l =  map.get(c) + 1; // 1
            }
            map.put(c, r);    //{a=t}
            r++;
        }

        return Math.max(max, r-l);

    }
}