README.md

1002. Find Common Characters

Given an array A of strings made only from lowercase letters, return a list of all characters that show up in all strings within the list (including duplicates). For example, if a character occurs 3 times in all strings but not 4 times, you need to include that character three times in the final answer.

You may return the answer in any order.

Example 1:

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

Example 2:

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

Note:

1. 1 <= A.length <= 100
2. 1 <= A[i].length <= 100
3. A[i][j] is a lowercase letter

Solutions (Python)

1. Count

class Solution:
    def commonChars(self, A: List[str]) -> List[str]:
        cnt1 = [100] * 26

        for wo in A:
            cnt2 = [0] * 26
            for ch in wo:
                cnt2[ord(ch) - 97] += 1

            for i in range(26):
                cnt1[i] = min(cnt1[i], cnt2[i])

        ret = []

        for i in range(26):
            ret.extend([chr(97 + i)] * cnt1[i])

        return ret