3. Longest Substring Without Repeating Characters

Medium

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) {
        int n = s.length();
        int maxValue = 0;
        int[] charArr = new int[128];
        Arrays.fill(charArr,-1);
        int i = 0;
        int j = 0;
        
        while(j<n){
            if(charArr[s.charAt(j)] >=i){
                i = charArr[s.charAt(j)] + 1;
            }
            
            charArr[s.charAt(j)] = j;
            maxValue = Math.max(maxValue,j-i+1);
            j++;
        }
        return maxValue;
        
    }
}