leetcode 題目：Longest Substring Without Repeating Characters

int lengthOfLongestSubstring(string s) {

        vector<int> dict(256, -1);
        int maxLen = 0, start = -1;
        for (int i = 0; i != s.length(); i++) {
cout << "the s[i] " << s[i] << endl;
cout << dict[s[i]] << endl;
            if (dict[s[i]] > start)
                start = dict[s[i]];
            dict[s[i]] = i;
            maxLen = max(maxLen, i - start);
        }
        return maxLen;
        

}

這種解答方式中就將dict當作字典來使用，鍵是字元，值是字元的索引。