class Solution {
    public String[] uncommonFromSentences(String s1, String s2) {
        Map<String, Integer> map = new HashMap<>();
        for(String word: s1.split(" ")){
            map.put(word, map.getOrDefault(word, 0) +1);
        }
        
        for(String word: s2.split(" ")){
            map.put(word, map.getOrDefault(word, 0) +1);
        }
        
        List<String> list = new ArrayList<>();
        for(Map.Entry<String, Integer> entry: map.entrySet()){
            if(entry.getValue() == 1)
                list.add(entry.getKey());
        }
        
        return list.toArray(new String[0]);
    }
}