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 Bracket Vault.
The wrong removal order changes gameplay and creates impossible replays.
How you win
- 1Recognize when Stack matching matches the clues
- 2Keep this true after every move: the stack holds exactly the unmatched opening brackets
- 3Reach the result within O(n)
Rules and pressure
- Target cost: O(n)
- State rule: the stack holds exactly the unmatched opening brackets
Lesson 1 of 3
Every opener pushes into the vault. A closer challenges only the top seal, so nesting naturally closes in reverse order.
Your call · After `([`, which opener does `]` challenge?