leetcode 3. Longest Substring Without Repeating Characters | 3. 无重复字符的最长子串（双指针+滑窗）

r囧r小猫 2022-09-02 11:40 26阅读 0赞

## 题目 ##

[https://leetcode.com/problems/longest-substring-without-repeating-characters/][https_leetcode.com_problems_longest-substring-without-repeating-characters]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70]

## 题解 ##

双指针+滑窗，维护一个 set，用来维护滑窗内的不同元素  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70]

class Solution { 
        public int lengthOfLongestSubstring(String s) { 
            HashSet<Character> set = new HashSet<>();
            int L = 0;
            int R = 0;
            int max = 0;
            while (R < s.length()) { 
                while (set.contains(s.charAt(R))) { 
                    set.remove(s.charAt(L++));
                }
                set.add(s.charAt(R++));
                max = Math.max(max, set.size());
            }
            return max;
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]

[https_leetcode.com_problems_longest-substring-without-repeating-characters]: https://leetcode.com/problems/longest-substring-without-repeating-characters/
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70]: /images/20220829/a321c5074e824f49aadc3daeb002ff4c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]: /images/20220829/86fed9f238c54a0797f460aa96415434.png