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

Example 1:

Input: "abcabcbb"Output: 3 Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: "bbbbb"Output: 1Explanation: The answer is "b", with the length of 1.

Example 3:

Input: "pwwkew"Output: 3Explanation: 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.

代码：

class Solution {public:    int lengthOfLongestSubstring(string s) {        map
     
       mp;        mp.clear();        int ans = 0, l = 0;        for(int i = 0; i < s.length(); i ++) {            if(mp[s[i]] == 0 || mp[s[i]] < l)                ans = max(ans, i - l + 1);            else l = mp[s[i]];                        mp[s[i]] = i + 1;        }        return ans;    }};