Search Suggestions (Trie / Prefix)

Question

## Problem

Given a product list and a search word typed character by character, return up to 3 lexicographically smallest suggestions for each prefix.

## Example
```
products=[mobile,mouse,moneypot], word=mou -> suggestions per prefix
```

## Constraints
- 1 ≤ n ≤ 10^4

## Approach
Trie or sorted array + binary search. Fits Elastic's search domain.