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We are given two arrays A and B of words.  Each word is a string of lowercase letters.

Now, say that word b is a subset of word a if every letter in b occurs in a, including multiplicity.  For example, "wrr" is a subset of "warrior", but is not a subset of "world".

Now say a word a from A is universal if for every b in B, b is a subset of a. 

Return a list of all universal words in A.  You can return the words in any order.

Example 1:

Input: A = ["amazon","apple","facebook","google","leetcode"], B = ["e","o"]Output: ["facebook","google","leetcode"]

Example 2:

Input: A = ["amazon","apple","facebook","google","leetcode"], B = ["l","e"]Output: ["apple","google","leetcode"]

Example 3:

Input: A = ["amazon","apple","facebook","google","leetcode"], B = ["e","oo"]Output: ["facebook","google"]

Example 4:

Input: A = ["amazon","apple","facebook","google","leetcode"], B = ["lo","eo"]Output: ["google","leetcode"]

Example 5:

Input: A = ["amazon","apple","facebook","google","leetcode"], B = ["ec","oc","ceo"]Output: ["facebook","leetcode"]

Note:

1. 1 <= A.length, B.length <= 10000
2. 1 <= A[i].length, B[i].length <= 10
3. A[i] and B[i] consist only of lowercase letters.
4. All words in A[i] are unique: there isn't i != j with A[i] == A[j].

Approach #1: String. [Java]

class Solution {    public List
    
      wordSubsets(String[] A, String[] B) {        int[] init = new int[26], temp;        for (String b : B) {            temp = counter(b);            for (int i = 0; i < 26; ++i) {                init[i] = Math.max(init[i], temp[i]);            }        }        List
     
       ret = new ArrayList<>();        for (String a : A) {            temp = counter(a);            int i = 0;            for (i = 0; i < 26; ++i) {                if (temp[i] < init[i]) break;            }            if (i == 26) ret.add(a);        }        return ret;    }        public int[] counter(String b) {        int[] temp = new int[26];        for (int i = 0; i < b.length(); ++i) {            temp[b.charAt(i)-'a']++;        }        return temp;    }}
     
    

Reference:

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