O(n) | Easy Solution |  Counter + Hash Table
Intuition\nYou should count every words, if the word appears only one time, you should add in your response\n\n# Approach\nConcatenate the strings, split, and u
# Intuition\nYou should count every words, if the word appears only one time, you should add in your response\n\n# Approach\nConcatenate the strings, split, and use `Counter()` to create a **hash table**\n\n# Complexity\n- Time complexity:\nO(n)\n\n- Space complexity:\nO(n)\n\n# Code\n```python3 []\nclass Solution:\n    def uncommonFromSentences(self, s1: str, s2: str) -> List[str]:\n        count = Counter((s1 + \' \' + s2).split(\' \'))\n        res = []\n        for i in count.keys():\n            if count[i] < 2:\n                res.append(i)\n\n        return res\n\n```
['Hash Table', 'Counting', 'Python', 'Python3']