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Shock Wave

USACO · 2025 · January · platinum-2

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binary-search

The organizer’s problem statement is available at the official source link.

sample trace

Shock Wave: binary search walkthrough

Shock Wave: use the linked editorial?s binary search idea on the published sample, then verify the displayed output.

Published input6 5 0 2 4 5 8 5 6 5 4 5 6 5 1 1 1 1 1 5 12 10 8 6 4 7 6 1 2 3 5 8 13 2 1000000000000000000 1000000000000000000modelAlgorithm ideaSearch a monotone boundary by repeatedly testing a midpoint with the editorial?s feasibility condition.task resultExpected output2 3 2 4 4 2000000000000000000
  1. 1

    Range

    Set the candidate interval for the quantity the task asks to minimize or maximize.
  2. 2

    Test

    Evaluate the task?s feasibility condition at the midpoint.
  3. 3

    Narrow

    Keep the half containing the true boundary until the answer is determined.
  4. 4

    Verify the sample

    Use the published sample output to check the result of this idea on the displayed input.
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