Enigma 152: The highways of Genoland
9 December 2013
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From New Scientist #1297, 18th March 1982 [link]
The five cities of Genoland are interconnected by four national highways A, B, C and D. They are also independently linked by four provincial highways 1, 2, 3 and 4. Each highway connects two cities and Geno is the only city which can be directly reached from every other city. A round trip of the five cities involves the five highways 1, 3, 4, B and C or 1, 2, A, C and D or 2, 3, A, B and C (not necessarily in the order given).
Which of the highways reach Geno?