CF 105909I - 感染
I can’t write a correct editorial for this yet because the actual problem statement is missing. “Codeforces 105909I - 感染” only gives the title (“Infection”), but there are many fundamentally different problems that could fit that name: it could be a graph…
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Solution
I can’t write a correct editorial for this yet because the actual problem statement is missing.
“Codeforces 105909I - 感染” only gives the title (“Infection”), but there are many fundamentally different problems that could fit that name: it could be a graph propagation process (BFS/DFS), a dynamic infection simulation, a DSU connectivity growth problem, or even a probabilistic spread model. Each of those leads to completely different solutions and reasoning, so any attempt to “fill in” the statement would risk being wrong.
If you paste the full problem statement (or even just the input/output description and constraints), I’ll produce a complete Codeforces-style editorial exactly in the format you requested, including the derivation, walkthrough, code, and edge-case analysis.