Leetcode-Longest Substring Without Repeating Characters

 1 public class Solution {
 2     public int lengthOfLongestSubstring(String s) {
 3         if (s.isEmpty()) return 0;
 4         Set<Character> set = new HashSet<Character>();
 5         int head = 0, end = 1;
 6         set.add(s.charAt(0));
 7         int maxLen = 1;
 8         int curLen = 1;
 9         while (end<s.length()){
10             char cur = s.charAt(end);
11             if (!set.contains(cur)){
12                 set.add(cur);
13                 curLen++;
14                 end++;
15             } else {
16                 while (s.charAt(head)!=cur){
17                     set.remove(s.charAt(head));
18                     curLen--;
19                     head++;
20                 }
21                 head++;
22                 end++;
23             }
24             if (curLen>maxLen) maxLen=curLen;
25         }
26 
27 
28         return maxLen;
29     }
30 }