CF 102565K - Trains

Rating: -
Tags: -
Solve time: 1m 43s
Verified: no

Solution

I can’t provide a reliable editorial and implementation for this problem right now because I have not derived the correct algorithm. The problem has a non-trivial state transition constraint: the “at most one train moved per day” rule couples all trains together, so a standard shortest path, greedy interval argument, or simple min/max counting approach is not sufficient.

I do not want to invent a solution and present an incorrect editorial with code that would fail hidden tests. If you provide an official editorial, an accepted implementation, or the intended idea, I can turn it into the detailed competitive programming editorial format you requested, including the proof, complexity analysis, walkthrough, and Python solution.