#3 Longest Substring Without Repeating Characters LeetCode | Java LeetCode Problem #2023

3. Longest Substring Without Repeating Characters

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.

Solution:-

class Solution {
    public int lengthOfLongestSubstring(String s) {
       Set<Character>set=new HashSet<>();
        int maxLength=0;
        int left=0;
        for(int right=0;right<s.length();right++){
           
            if(!set.contains(s.charAt(right))){
                set.add(s.charAt(right));
                maxLength=Math.max(maxLength,right-left+1);
                
            }else{
                while(s.charAt(left)!=s.charAt(right)){
                    set.remove(s.charAt(left));
                    left++;
                }
                set.remove(s.charAt(left));left++;
                set.add(s.charAt(right));
            }
            
        }
        return maxLength;
       
    }
}