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The Postfix Engine

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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 Postfix Engine.

The wrong removal order changes gameplay and creates impossible replays.

How you win

  1. 1Recognize when Operand stack evaluation matches the clues
  2. 2Keep this true after every move: the stack contains exactly the unresolved values produced by the processed tokens
  3. 3Reach the result within O(n)

Rules and pressure

  • Target cost: O(n)
  • State rule: the stack contains exactly the unresolved values produced by the processed tokens
Lesson 1 of 3

Socket order changes subtraction and division. First pop RIGHT, second pop LEFT: compute 8-3=5, then 5/2=2.

Your call · Stack after 8 3 -?

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