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The Echoing Panes

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Problem context and objectives
Mission briefing

Live-ops game engineer · A multiplayer arena is reporting bursts of lag

Find the smallest or strongest contiguous time window: The Echoing Panes.

Scanning the entire history after every event cannot keep up with live players.

How you win

  1. 1Recognize when Rolling window output matches the clues
  2. 2Keep this true after every move: the running sum contains exactly the values from left through right
  3. 3Reach the result within O(n)

Rules and pressure

  • Target cost: O(n)
  • State rule: the running sum contains exactly the values from left through right
Lesson 1 of 3

Build the first fixed-window sum and record it immediately. If you skip that append, the first answer disappears.

Your call · The first sum is 8. What happens next?

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