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Graph TheorySuperchallengeEulerian and Hamiltonian Graphs

Eulerian and Hamiltonian Graphs · Superchallenge problem

Split 88 people into two groups of four, L={0,1,2,3}L=\{0,1,2,3\} and R={4,5,6,7}R=\{4,5,6,7\}, and suppose every person in LL is friends with every person in RR (and no one is friends within their own group) — the complete bipartite graph K4,4K_{4,4}. Counting two seating arrangements around a circular table as the same whenever one is a rotation or reflection of the other, how many distinct Hamiltonian cycles (seating arrangements where every neighbor pair are friends) does K4,4K_{4,4} have?