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0916-word-subsets

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Problem Description

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"]

Solution

public List<String> wordSubsets(String[] A, String[] B) {
    int[] bmax = frequency("");
    
    for (String s : B) {
        int[] count = frequency(s);
        for (int i = 0; i < 26; i++) {
            bmax[i] = Math.max(bmax[i], count[i]);
        }
    }
    
    List<String> res = new ArrayList<>();
    for (String s : A) {
        int[] count = frequency(s);
        boolean found = true;
        for (int i = 0; i < 26; i++) {
            if (bmax[i] > count[i]) {
                found = false;
                break;
            }
        }
        if (found)
            res.add(s);
    }
    
    return res;
}

private helper method

private int[] frequency(String s) {
    int[] count = new int[26];
    for (char c : s.toCharArray()) {
        count[c - 'a']++;
    }
    return count;
}

Test

Compile with javac Solution.java and run with java Solution.

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