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MathNet 2019-part-08 — 179 problems (EN–VI) Question 44

Math Olympiad Vault · MathNet 2019-part-08 — 179 problems (EN–VI)

Question 44

In Middle-Earth, nine cities form a $3$ by $3$ grid. The top left city is the capital of Gondor and the bottom right city is the capital of Mordor. How many ways can the remaining cities be divided among the two nations such that all cities in a country can be reached from its capital via the grid-lines without passing through a city of the other country?