In a loop, unless it passes through the initial node twice and passes through each node exactly once, it is called a Hamilton loop, and each node in the Hamilton loop is an even node.

Through the above points, we can draw the conclusion that there is no Hamiltonian loop in the above diagram.

This problem is based on finding Hamiltonian circuits, but the corresponding graph is a weighted undirected graph. Down there.

This article ends here. Next, there will be an article devoted to the problem of traveling salesmen. Thank you!