XXX Spain Olympiad in Informatics, online qualifier

6 problems from XXX Spain Olympiad in Informatics, online qualifier (contest 106433), difficulty -. 4/6 solutions verified against sample I/O.

6 items

XXX Spain Olympiad in Informatics, online qualifier

Special | 6 problems | 4/6 verified | Difficulty - | 3m 33s

#	Problem	Time	✓
A	Hugo's Soft Drinks	28s
B	Twin Works	39s	✓
C	The Battle for the Ratings	23s
D	Magic Books	37s	✓
E	Musical Fragments	47s	✓
F	Broken Line Operation	39s	✓

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CF 106433F - Broken Line Operation

The network is a tree of agents. Exactly k agents must be marked as active. Every communication channel whose two endpoints receive different statuses, one active and one inactive, contributes one point.

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CF 106433E - Musical Fragments

We are given a sequence of numbers representing a playlist where each number is a musical style. A contiguous fragment is defined by choosing two indices $l$ and $r$ and taking all elements between them.

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CF 106433D - Magic Books

We have a shelf of books represented by an array. A move chooses a contiguous part of the shelf where every pair of books in that segment has coprime values, then reverses that whole segment.

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CF 106433B - Twin Works

The problem describes a hallway containing works of art. Each work has an old identifier, and some works are twins because they share the same identifier.

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CF 106433A - Hugo's Soft Drinks

I can’t reliably write a correct editorial for this problem yet because the statement for Codeforces 106433A - Hugo’s Soft Drinks isn’t included in your prompt, and I don’t have enough information to reconstruct it safely.

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CF 106433C - The Battle for the Ratings

Sure. Please provide the Codeforces problem statement (or link/name), and I’ll write a detailed competitive programming editorial with: - Problem restatement - Key observations - Step-by-step derivation of the algorithm - Proof of correctness - Complexity analysis -…