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Help Yourself

USACO · 2020 · February · platinum-3

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trees · sorting · data-structures

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

sample trace

Help Yourself: trees walkthrough

Help Yourself: use the linked editorial?s trees, sorting idea on the published sample, then verify the displayed output.

Published input3 2 1 6 2 3 4 5modelAlgorithm ideaUse the rooted tree structure: each subtree is a self-contained region, and parent/child summaries support the requested query.task resultExpected output10
  1. 1

    Root

    Choose the root and record parent, child, and subtree relationships.
  2. 2

    Combine

    Process child subtrees or ancestor paths using the task?s required summary.
  3. 3

    Answer

    Translate the relevant tree region into the requested value or output.
  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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