Problem context and objectives
Mission briefing
Game event engineer · Actions arrive faster than the world can resolve them
Process events in the exact order promised by the data structure: The First Voice Stream.
The wrong removal order changes gameplay and creates impossible replays.
How you win
- 1Recognize when Frequency queue matches the clues
- 2Keep this true after every move: the queue front is the earliest processed character with frequency one
- 3Reach the result within O(n)
Rules and pressure
- Target cost: O(n)
- State rule: the queue front is the earliest processed character with frequency one
New words in this mission
Open a term for a plain-language explanation.durable queue+
A waiting line that keeps work until a consumer finishes it. It absorbs bursts and lets failed work be retried.
Lesson 1 of 3
The frequency board determines eligibility; the queue preserves arrival order. Remove repeated fronts, then emit the earliest unique voice.
Your call · After the second a arrives, which voice is emitted?