Detect and remove matched words in a char stream

You are processing a stream of characters (arriving one-by-one). You are also given a list of target words. Each time a new character arrives, it is appended to the end of the current stream buffer. After appending, if the buffer contains **any** target word as a **contiguous substring**, you must: 1. **Return/report** a matched word (assume if multiple words match, you may return any one of them, but you must define and follow a consistent rule such as “return the first match found” or “return the longest match”). 2. **Delete** that occurrence of the matched word from the buffer (remove exactly those characters), then continue processing future characters. ### Clarifications to make explicit in your solution - Can matches overlap? If multiple matches exist simultaneously, which one do you remove? - Do you remove only one word per incoming character, or repeatedly remove until no word remains? ### Input/Output (one reasonable interface) - Input: `words: List[str]`, and a sequence of calls `query(c: char)`. - Output per call: the matched word (or empty string / null if no match). The internal buffer should reflect deletions. ### Constraints (typical interview-scale) - Number of words: up to ~10^4 - Total length of all words: up to ~10^5 - Stream length can be large (online processing required).