Filter System with Dynamic Blacklist

Design a filter with processFilter / processInput / emit: emit a value when it appears in the input stream and is not currently blacklisted. Follow-up adds an updateFlag so filter edits re-emit state changes — emit(false, v) when a previously-seen value becomes blocked, emit(true, v) when it becomes visible again. Problem Overview Design a filter system that processes a stream of integer inputs against a dynamically maintained blacklist. Implement three methods: processFilter(int value) — add or remove value from the blacklist filter (dynamic toggle). processInput(int value) — feed one value from the input stream. emit(int value) — system output hook for a value. Rule: when a value arrives via processInput and is not currently in the filter, the system calls emit(value). You are expected to implement the full class and write your own test cases. Follow-up Add an updateFlag and change the signatures: processFilter(boolean updateFlag, int value) processInput(int value) emit(boolean updateFlag, int value) updateFlag controls whether the filter operation adds or removes value. When a filter update flips the visibility of a value that has already appeared in the input, emit the state change: emit(false, value) when an already-seen value becomes newly blocked. emit(true, value) when a blocked-but-already-seen value becomes visible again. Sample Cases The published trace (operations in time order): processFilter +1 +2 -1 +3 processInput 1 3 emit +3 +1 -3 Notes The base method needs only a set for the current blacklist; the follow-up additionally requires tracking every value seen so far so that a filter edit can replay its effect on already-seen values. The published trace is terse — clarify the exact ordering and which events trigger emit with the interviewer before coding. Edge cases to enumerate yourself: a value added then removed from the filter, a value appearing in the input before vs. after it is filtered, and repeated inputs of the same value.