1002. Find Common Characters

class Solution {
public:
    vector<string> commonChars(vector<string>& words) 
    {
        vector<string> ans;
        vector<int> minFreq(26, INT_MAX);

        for(int i=0; i<words.size(); i++)
        {
            vector<int> charFreq(26, 0);

            for(int j=0; j<words[i].size(); j++)
            {
                int index = (words[i][j] - 'a');
                charFreq[index]++;
            }

            for(int i=0; i<26; i++)
            {
                minFreq[i] = min(minFreq[i], charFreq[i]);
            }
        }

        for(int i=0; i<26; i++)
        {
            int n = minFreq[i];
            while(n>0)
            {
                string s = "";
                char ch = 'a'+i;
                s+=ch;
                ans.push_back(s);
                n--;
            }
        }
        return ans;
    }
};