Return Indices of Words Containing a Given Character
Company: Google
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
# Return Indices of Words Containing a Given Character
You are given a 0-indexed array of strings `words` and a character `x`.
Return an array containing the indices of all words that contain `x`. Each qualifying index should appear once. The returned indices may be in any order.
### Examples
**Example 1**
```text
Input: words = ["map","mammal","sky","map"], x = "m"
Output: [0,1,3]
```
Indices `0`, `1`, and `3` contain `'m'`. The repeated word `"map"` occurs at two different indices, so both indices qualify. `"mammal"` contributes its index only once despite having several occurrences of `'m'`. Any ordering of these three indices is valid.
**Example 2**
```text
Input: words = ["stone","river"], x = "z"
Output: []
```
Neither word contains `'z'`, so return an empty array.
### Constraints
- `1 <= words.length <= 50`.
- `1 <= words[i].length <= 50`.
- `x` is a lowercase English letter.
- Each `words[i]` contains only lowercase English letters.
### Clarifying Questions
- Should we return words or indices? Return their 0-based indices.
- If a word contains the character multiple times, should its index repeat? No; the index represents one qualifying word occurrence.
- Can identical words occur at different positions? No uniqueness guarantee is given; inspect each position independently.
- Must indices be sorted? No; any order is allowed.
- What happens when there are no matches? Return an empty array.
### C++ Interface
```cpp
class Solution {
public:
vector<int> findWordsContaining(vector<string>& words, char x) {
}
};
```
### Reasoning Checkpoints
- Distinguish repeated characters within one word from repeated words at different indices.
- Include every matching index and exclude every nonmatching index.
- Respect the any-order result contract and account for the output size.
```hint Stop after the first match within a word
Inspect each word's characters. Once the target character is found, record that word's index and move to the next word.
```
Overview: Return every word index whose string contains the target lowercase character, including separate positions with identical words and allowing any output order.