sliding_window_longest_substring_number_3_leetcode.java

class Solution {
    public int lengthOfLongestSubstring(String s) {
        int a_pointer = 0;
        int b_pointer = 0;
        int max = 0;
        
        HashSet<Character> hash_set = new HashSet();
        
        while(b_pointer<s.length()){
            if(!hash_set.contains(s.charAt(b_pointer))){
                hash_set.add(s.charAt(b_pointer));
                b_pointer++;
                max = Math.max(hash_set.size(), max);
            }else{
                hash_set.remove(s.charAt(a_pointer));
                a_pointer++;
            }
        }
        return max;
    }
}