Talk:Yen's algorithm

Apologies if I am misunderstanding the algorithm, but as stated, I'm not sure what guarantees that a spur path doesn't circle back and intersect a node that is already on the root path, resulting in a cyclic result? Are these to be removed later in an unstated step? Its hard to imagine this scenario in the illustrated example (a directed graph), but particularly with undirected graphs (edges can be traversed both ways) I think this could happen very readily.