916-word-subsets¶

Description¶

You are given two string arrays words1 and words2.

A string b is a subset of string 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".

A string a from words1 is universal if for every string b in words2, b is a subset of a.

Return an array of all the universal strings in words1. You may return the answer in any order.

Example 1:

Input: words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["e","o"]
Output: ["facebook","google","leetcode"]

Example 2:

Input: words1 = ["amazon","apple","facebook","google","leetcode"], words2 = ["l","e"]
Output: ["apple","google","leetcode"]

Constraints:

1 <= words1.length, words2.length <= 10⁴
1 <= words1[i].length, words2[i].length <= 10
words1[i] and words2[i] consist only of lowercase English letters.
All the strings of words1 are unique.

Solution(Python)¶

class Solution(object):
    def wordSubsets(self, A, B):
        def count(word):
            ans = [0] * 26
            for letter in word:
                ans[ord(letter) - ord('a')] += 1
            return ans

        bmax = [0] * 26
        for b in B:
            for i, c in enumerate(count(b)):
                bmax[i] = max(bmax[i], c)

        ans = []
        for a in A:
            if all(x >= y for x, y in zip(count(a), bmax)):
                ans.append(a)
        return ans