How many Hamiltonian cycles are there in a graph with n vertices?

76 Views Asked by At

How many eulerian cycles are there in a graph with n vertices? The way that I see it there would be $\frac{n!}{(n!)(n-n)!}$ but that simplifies to 1 cycle and I know that there are more cycles than that. What am I missing here? In this case the order of the vertices does not matter.

1

There are 1 best solutions below

1
On BEST ANSWER

The amount of hamiltonian cycles in a graph is $\frac{1}{2}(n-1)!$ since the graph is un-directed you do not have a choice for the first vertex and every point after that is $(n-1)(n-2)...$ or $(n-1)!$ and since there are 2 ways to choose the same vertex you end up with $\frac{1}{2}(n-1)!$.