884 LeetCode 两句话中的不常见单词

题目描述：
思路：方法一：
使用哈希表遍历两遍来查找；
方法二：
把两个字符串合并成一个字符串，找到出现一次的单词

class Solution {
public:
    vector<string> uncommonFromSentences(string A, string B) {
        A+=" ";
        B+=" ";
        map<string,int>cnt;
        map<string,int>num;
        vector<string>words;
        vector<string>words2;
        vector<string>cur;
        vector<string>cur2;
        vector<string>res;
        string letter="";
        for(int i=0;i<A.size();i++){
            if(A[i]!=' '){
                letter+=A[i];
            }
            else {
                cnt[letter]++;
                words.push_back(letter);
                letter="";}
        }
        for(int i=0;i<words.size();i++){
            if(cnt[words[i]]==1)
            cur.push_back(words[i]);
        }
        letter="";
        for(int i=0;i<B.size();i++){
            if(B[i]!=' '){
                letter+=B[i];
            }
            else {
                num[letter]++;
                words2.push_back(letter);
                letter="";}
        }
        for(int i=0;i<words2.size();i++){
            if(num[words2[i]]==1)
            cur2.push_back(words2[i]);
        }
        for(int i=0;i<cur.size();i++){
            if(num[cur[i]]==0)
            res.push_back(cur[i]);
        }
        for(int i=0;i<cur2.size();i++){
            if(cnt[cur2[i]]==0)
            res.push_back(cur2[i]);
        }
        return res;
    }
};

class Solution {
public:
    vector<string> uncommonFromSentences(string A, string B) {
        A+=" ";
        string C=A+B;
        C+=" ";
        map<string,int>cnt;
        vector<string>words;
        vector<string>res;
        string letter="";
        for(int i=0;i<C.size();i++){
            if(C[i]!=' '){
                letter+=C[i];
            }
            else {
                cnt[letter]++;
                words.push_back(letter);
                letter="";}
        }
        for(int i=0;i<words.size();i++){
            if(cnt[words[i]]==1)
            res.push_back(words[i]);
        }
        return res;
    }
};