原题：

https://leetcode.com/problems/longest-substring-without-repeating-characters/description/

 

参考：

 

解法：

class Solution {    public int lengthOfLongestSubstring(String s) {        HashMap
     
       map = new HashMap<>();                int res = 0, i = 0,left=0;                while(i
      
       =left) left = map.get(ch)+1;            else res = Math.max(res,i-left+1);            map.put(ch,i++);        }        return res;    }}