187. Repeated DNA Sequences

    public List<String> findRepeatedDnaSequences(String s) {
        
        Set<String> resultSet = new HashSet<String>();
        Set<String> seen = new HashSet<>(); // 过滤重复的目标字符串
        
        for (int i = 0; i + 9 < s.length(); i++) {
            String tmp = s.substring(i, i + 10);
            if(!seen.add(tmp)) 
                resultSet.add(tmp);
        }
        
        return new ArrayList<>(resultSet);
    }