题目
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.
解题思路
将所有B中的所有单词，凑成一个单词，使这个字符串包含b中所有的单词，遍历A中所有单词，只要包含这个单词就可以
代码
class Solution:
def wordSubsets(self, A: List[str], B: List[str]) -> List[str]:
target = defaultdict(int)
for word in B:
for c, v in Counter(word).items():
target[c] = max(target[c], v)
res = []
for word in A:
ct = Counter(word)
for c, v in target.items():
if c not in ct or v > ct[c]:
break
else:
res.append(word)
return res
