3.无重复字符的最长子串.java

import java.util.HashSet;
import java.util.Set;

/*
 * @lc app=leetcode.cn id=3 lang=java
 *
 * [3] 无重复字符的最长子串
 */
class Solution {
    public int lengthOfLongestSubstring(String s) {
        int max = 0;
        Set<Character> set = new HashSet<>();
        int i = 0;
        int j = 0;
        
        while(j < s.length()){
            if(set.contains(s.charAt(j))){
                set.remove(s.charAt(i++));
            }else{
                set.add(s.charAt(j++));
                max = Math.max(max, set.size());
            }
        }
        return max;
    }
}