884. Uncommon Words from Two Sentences

https://leetcode-cn.com/problems/uncommon-words-from-two-sentences/
https://tianchi.aliyun.com/oj/338592228998370026/357527484118536804
We are given two sentences A and B.  (A sentence is a string of space separated words.  Each word consists only of lowercase letters.)

A word is uncommon if it appears exactly once in one of the sentences, and does not appear in the other sentence.

Return a list of all uncommon words.

You may return the list in any order.

Example 1:

Input: A = "this apple is sweet", B = "this apple is sour"
Output: ["sweet","sour"]
Example 2:

Input: A = "apple apple", B = "banana"
Output: ["banana"]

Note:

0 <= A.length <= 200
0 <= B.length <= 200
A and B both contain only spaces and lowercase letters.

unordered_map<string, int> mapp;
A = A + " " + B;
istringstream str(A);
string s;
vector ans;
while(str >> s) ++mapp[s];
for(auto m:mapp)
if(m.second == 1)
ans.push_back(m.first);
return ans;