# leetcode\_1002

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

## Solutions

1. **hashmap**

```cpp
class Solution {
public:
    vector<string> commonChars(vector<string>& A) {
        vector<int> count(26, 100);
        for (auto & w : A) {
            vector<int> cur(26);
            for (auto c : w)
                cur[c - 'a']++;
            for (int i = 0; i < 26; i++)
                count[i] = min(count[i], cur[i]);
        }

        vector<string> res;
        for (int i = 0; i < 26; i++)
            for (int j = 0; j < count[i]; j++)
                res.emplace_back(1, i + 'a');
        return res;
    }
};
```