class Solution {public:    int lengthOfLongestSubstring(string s) {        string res="";        int maxlen=0;        for(int i=0;i
     
      res.length())?maxlen:res.length();            }            else            {                res.erase(0,res.find(s[i])+1);                res+=s[i];            }        }        return maxlen;    }};