Return the Multiset of Characters Present in Every Word
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
Return an array of one-character strings for all characters common to every word in `words`, including repeated occurrences. A character appears as many times as its smallest count in any input word. Return the characters in any order.
```cpp
class Solution {
public:
vector<string> commonChars(vector<string>& words);
};
```
### Examples
**Example 1:**
```text
Input: words = ["aabb","ababa","baa"]
Output: ["a","a","b"]
Explanation: Every word contains at least two a characters and at least one b; baa prevents a second common b.
```
**Example 2:**
```text
Input: words = ["abc","def"]
Output: []
Explanation: No character occurs in both words.
```
### Constraints
- `1 <= words.length <= 100`.
- `1 <= words[i].length <= 100`.
- Words contain only lowercase English letters.
### Contract considerations
The returned elements are strings of length one, preserving the original `vector<string>` interface.
```hint Read the boundary condition
For each letter, what is the most copies that every word can supply?
```
### What a Strong Answer Covers
The returned elements are strings of length one, preserving the original `vector<string>` interface.
### Follow-up Questions
Optional practice extension, separate from the original task: How could you support strings arriving one at a time?
Overview: Return the Multiset of Characters Present in Every Word. Return an array of one-character strings for all characters common to every word in words, including repeated occurrences.
