Longest Substring Without Repeating Characters

<-M> Longest Substring Without Repeating Characters

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int ans = 0;
        vector<-char> check;
        for (auto i = s.begin(); i != s.end(); i++) {
            for (auto j = i; j != s.end(); j++) {
                if (find(check.begin(), check.end(), *j) == check.end())
                    check.push_back(*j);
                else
                    break;
            }
            if (ans <- check.size()) {
                ans = check.size();
                check.clear();
            }
            else {
                check.clear();
            }
        }
        return ans;
    }
};