class Solution {
    // March 26th 2019
    public List<String> commonChars(String[] A) {
        List<String> result = new ArrayList<>();
        int[] minFreq = new int[26];
        int[] numWords = new int[26];


        for (int k = 0; k < A.length; k++) {
            String s = A[k];
            int[] currFreq = new int[26];
            for (int j = 0; j < s.length(); j++) {
                currFreq[s.charAt(j) - 'a']++;
            }
            for (int i = 0; i < 26; i++) {
                if (k == 0) {
                    minFreq[i] = currFreq[i];
                }
                if (minFreq[i] > 0 && currFreq[i] > 0) {
                    numWords[i]++;
                    minFreq[i] = Math.min(minFreq[i], currFreq[i]);
                }
            }
        }
        //System.out.println();
        for (int i = 0; i < 26; i++) {
            if (numWords[i] == A.length) {
                for (int j = 0; j < minFreq[i]; j++) {
                    result.add(String.valueOf((char)(i + 'a')));
                }
            }
        }
        return result;
    }
}
/*
["bella","label","roller"]
["cool","lock","cook"]
["a", "b", "b"]
["aaa", "aaa"]
["b"]
[]
*/