class Solution {
public:
    int longestSubstringWithoutDuplication(string s) {

        if(!s.length()) return 0;

        int res = 1, i = 0, j = 0;
        bool tag[27] = {false};

        while (i < s.length() && j < s.length())
        {
            while(j < s.length() && !tag[s[j] - 'a'])
            {
                tag[s[j++] - 'a'] = true;
            }
            res = max(res, j-i);
            while(i < s.length() && s[i] != s[j])
            {
                tag[s[i++] - 'a'] = false;
            }
            i++ & j++;
        }

        return res;

    }
};