Longest substring without repeating characters

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        unordered_map<char, int>map;
        int l=0, r=0, n=s.length();
        int len=0;
        while(r<n){
            if(map.find(s[r]) != map.end()){
                l= max(l,map[s[r]]+1);
               
            }
            
            map[s[r]]= r;
                // r++;
            len=max(len, r-l+1);
            r++;
        }
        
        
        return len;
    }
};