记录最大的起始位置+hash

int lengthOfLongestSubstring(string s) {
        map<char, int> charMap;
        int curLen, maxLen = 0,lastIndex = -1;
        for (int i = 0; i < s.size(); i++)
        {
            if (charMap.find(s[i]) != charMap.end() && lastIndex < charMap[s[i]])
                    lastIndex = charMap[s[i]];
            curLen = i - lastIndex;
            maxLen = max(maxLen,curLen);
            charMap[s[i]] = i;
        }
        return maxLen;
    }

Longest Substring Without Repeating Characters[leetcode]