Leetcode - Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.

Examples:

Given "abcabcbb", the answer is "abc", which the length is 3.

Given "bbbbb", the answer is "b", with the length of 1.

Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

     int lengthOfLongestSubstring(string s) {        int ans= 0, l = 0 ;        int map[256] = {0};              for(int i = 0 ; i < s.size(); i ++) {            if(map[s[i]] != 0 && map[s[i]] >= l) {                 ans= (i - l)  > ans ? (i  - l) : ans;                l = map[s[i]]   ;             }           if( i + 1 - l  > ans) ans= i + 1 - l ;              map[s[i]] = i + 1 ;        }                return anw;    }

看起来更加牛B 的代码是这个：

   int lengthOfLongestSubstring(string s) {       int n = s.size(), ans = 0;       int index [128] = {0}; // current index of character                                // try to extend the range [i, j]       for (int j = 0, l = 0; j < n; j++) {        l = std::max(index[s[j]], l);        ans = std::max(ans, j - l + 1);        index[s[j]] = j + 1;       }       return ans;    }