Given a string s, find the length of the longest

substring

without repeating characters.

Example 1:

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

Example 2:

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

Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

Constraints:

• 0 <= s.length <= 5 * 104
• s consists of English letters, digits, symbols and spaces.
• 使用双指针+ hashset 存储 和loop

class Solution {
    public int lengthOfLongestSubstring(String s) {
        Set<Character> set = new HashSet<>();
        int maxLength = 0;
        int i = 0, j = 0;
        while(j < s.length())
            if(!set.contains(s.charAt(j))){
                set.add(s.charAt(j));
                j++;
                maxLength = Math.max(maxLength, j - i );
            } else {
                set.remove(s.charAt(i));
                i ++;
            }
      
        return maxLength;
    }
}