LeetCode 884. 两句话中的不常见单词

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。

class Solution {
public:
    vector<string> uncommonFromSentences(string A, string B) {
        unordered_map<string, int> mA, mB;
        int i;
        string str;
        for(i = 0; i < A.size(); ++i)
        {
        	if(A[i] == ' ')
        	{
        		mA[str]++;
        		str = "";
        	}
        	else
        	{
        		str.push_back(A[i]);
        		if(i == A.size()-1)
        			mA[str]++;
        	}
        }
        str = "";
        for(i = 0; i < B.size(); ++i)
        {
        	if(B[i] == ' ')
        	{
        		mB[str]++;
        		str = "";
        	}
        	else
        	{
        		str.push_back(B[i]);
        		if(i == B.size()-1)
        			mB[str]++;
        	}
        }
        vector<string> ans;
        for(auto it = mA.begin(); it != mA.end(); ++it)
        {
        	if(it->second == 1 && mB.find(it->first) == mB.end())
        		ans.push_back(it->first);
        }
        for(auto it = mB.begin(); it != mB.end(); ++it)
        {
        	if(it->second == 1 && mA.find(it->first) == mA.end())
        		ans.push_back(it->first);
        }
        return ans;
    }
};