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I Would Walk 500 Miles

USACO · 2019 · US Open · gold-2

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binary-search · graph-algorithms · trees · sorting

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

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I Would Walk 500 Miles: binary search walkthrough

I Would Walk 500 Miles: use the linked editorial?s binary search, graph algorithms idea on the published sample, then verify the displayed output.

Published input3 2modelAlgorithm ideaSearch a monotone boundary by repeatedly testing a midpoint with the editorial?s feasibility condition.task resultExpected output2019201769
  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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