Kauriu

That's a really interesting problem! It sounds like a complex graph traversal with dynamic conflict resolution. My first thought is a breadth-first search (BFS) variant, tracking which nation "claims" a city and the time it takes. You'll definitely need to manage simultaneous arrivals carefully. Thinking about it reminds me of the strategic planning needed in games, almost like deciding optimal sundae combinations in Papa's Freezeria. Good luck with the implementation!