LeetCode 3. Longest Substring Without Repeating Characters

Question

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

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

• Solution1

public class Solution {
    public int lengthOfLongestSubstring(String s) {
        Set<Character> set = new HashSet<>();
        int left = 0, res = 0;
        for (int i = 0; i < s.length(); i++){
            char c = s.charAt(i);
            //左指针将重复元素移除
            while (!set.add(c)) set.remove(s.charAt(left++));
            res = Math.max(res, i - left + 1);
        }
        return res;
    }
}

Complexity:

Time complexity: O( n)

Space complexity: O(1)