【leetcode】3. 无重复字符的最长子串

int lengthOfLongestSubstring(char * s){
    int i, j = 0, count = 0, max = 0, index[128] = { 0 }, start = 0;
    for (i = 0; s[i] != ''; i++)
    {
        if (index[s[i]]>start)   //index用来储存出现重复字符时
        {                       //子串起始下标应移动到的地方
            count = i - start;
            if (count>max)
            {
                max = count;
            }
            start = index[s[i]];
        }
        index[s[i]] = i + 1;
    }
    count = i - start;
    return count>max ? count : max;
}