# LeetCode 1002. Find Common Characters

## Description

https://leetcode.com/problems/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

## Explanation

Find intersects characters between all the words, and count their minimum occurrences in words.

## Python Solution

``````class Solution:
def commonChars(self, A: List[str]) -> List[str]:

intersect = set(A)

for word in A[1:]:
intersect = intersect.intersection(set(word))

counter = {}
for key in intersect:
counter[key] = sys.maxsize

for key in intersect:
for word in A:
counter[key] = min(counter[key], word.count(key))

results = []
for key, value in counter.items():
for i in range(value):
results.append(key)

return results``````
• Time Complexity: O(N)
• Space Complexity: O(N)