916. Word Subsets

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<String> 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<String> 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:

https://leetcode.com/problems/word-subsets/discuss/175854/C%2B%2BJavaPython-Straight-Forward