Word Subsets — LeetCode 916 Python Solution

The problem

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.

Python solution

class Solution:
    def wordSubsets(self, words1: List[str], words2: List[str]) -> List[str]:
        cnt = Counter()
        for b in words2:
            t = Counter(b)
            for c, v in t.items():
                cnt[c] = max(cnt[c], v)
        ans = []
        for a in words1:
            t = Counter(a)
            if all(v <= t[c] for c, v in cnt.items()):
                ans.append(a)
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 916. Word Subsets is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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