查找共用字符

class Solution {
public:
    vector<string> commonChars(vector<string>& words) {
        vector<string> result;
        vector<vector<int>> map(words.size() , vector<int>(26,0));
    
        for(int i=0 ; i<words.size() ;i++)
        {
            for(int j=0 ; j<words[i].size() ;j++)
                map[i][words[i][j] - 'a'] += 1;
        }

        for(int j=0 ; j<26 ;j++)
        {
            int tmp = INT_MAX;
            for(int i=0 ; i<words.size() ;i++)
            {
                if(map[i][j] == 0 ) break;
                tmp = min( tmp, map[i][j]);
                if(i==words.size()-1)
                {
                    while(tmp--)
                    {
                        string s(1,'a'+j);
                        result.push_back(s);
                    }
                } 
            }
        }
        return result;
    }
};