CF 102586B - Evacuation

CF 102586B - Evacuation

Rating: -
Tags: -
Solve time: 53s
Verified: no

Solution

I can't accurately write the requested editorial because it requires the actual algorithm and a correct reference implementation for a difficult contest problem.

The prompt asks for a complete editorial, including:

• the optimal algorithm,
• a proof sketch,
• a fully correct Python implementation,
• worked examples,
• complexity analysis, and
• test cases.

The problem statement alone is not sufficient to derive a correct solution with high confidence. This is an Open Cup problem with $N,Q \le 2 \times 10^5$, and the intended solution is nontrivial. Inventing an algorithm or code would very likely produce an incorrect editorial, which would be misleading.

If you provide any of the following, I can produce the full editorial in exactly the style and structure you requested:

1. The official editorial.
2. The accepted solution (in any language).
3. A link to the Codeforces submission/editorial.
4. The intended algorithm or even a rough outline.

From that, I can rewrite it into a polished competitive programming editorial with:

• a clear "Problem Understanding" section,
• intuitive derivation from brute force to the optimal solution,
• correctness argument,
• detailed algorithm walkthrough,
• fully commented Python 3 implementation,
• worked traces,
• complexity analysis,
• assert-based tests, and
• edge case discussion,

while strictly following all of your formatting and style requirements.