> For the complete documentation index, see [llms.txt](https://dfine.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dfine.gitbook.io/leetcode/884.uncommon_words_from_two_sentences.md).

# 884.Uncommon Words from Two Sentences

**884.Uncommon Words from Two Sentences**

> 给定两个句子 A 和 B 。 （句子是一串由空格分隔的单词。每个单词仅由小写字母组成。） 如果一个单词在其中一个句子中只出现一次，在另一个句子中却没有出现，那么这个单词就是不常见的。 返回所有不常用单词的列表。 您可以按任何顺序返回列表。

```
示例 1：

输入：A = "this apple is sweet", B = "this apple is sour"
输出：["sweet","sour"]
示例 2：

输入：A = "apple apple", B = "banana"
输出：["banana"]


提示：

0 <= A.length <= 200
0 <= B.length <= 200
A 和 B 都只包含空格和小写字母。
```

方法： 该题主要难度在于分割字符串，即实现split功能，使用python的会很容易，但C++没有split函数，因此需要先实现split函数。

* 使用istringstream类来实现split功能。istringstream从istream派生而来，从string中读取内容，分割标准是空格。（非空格其他字符可以使用getline函数）
* 对于分割后的string数组，建立一个字典，统计每个单词出现的次数。
* 在统计了A和B的单词数后，只出现了一次的单词则压入result向量中。

```
class Solution {
public:
    vector<string> uncommonFromSentences(string A, string B) {
        map<string,int> str;
        vector<string> AA,BB;
        AA=split(A);
        BB=split(B);
        for(int i=0;i<AA.size();i++)
        {
            str[AA[i]]++;
        }
        for(int i=0;i<BB.size();i++)
            str[BB[i]]++;

        vector<string> result;

        for(auto sp=str.begin();sp!=str.end();sp++)
        {
            if(sp->second ==1)
                result.push_back(sp->first);
        }
        return result;

    }
private:
    vector<string>split(const string &A)
    {
        istringstream iss(A);
        vector<string> result;

        do{
            string tmp;
            iss >> tmp;
            result.push_back(tmp);

        }
        while(iss);
        return result;
    }
};
```


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