Find Common Characters

Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order.

Example 1:

Input: words = ["bella","label","roller"]
Output: ["e","l","l"]

Example 2:

Input: words = ["cool","lock","cook"]
Output: ["c","o"]

Constraints:

• 1 <= words.length <= 100
• 1 <= words[i].length <= 100
• words[i] consists of lowercase English letters.

SOLUTION:

from collections import Counter

class Solution:
    def commonChars(self, words: List[str]) -> List[str]:
        common = set.intersection(*[set(w) for w in words])
        ctrs = [Counter(w) for w in words]
        ans = []
        for c in common:
            ans += [c] * min([ctr[c] for ctr in ctrs])
        return ans