That doesn't actually work, because a DAG only lacks directed cycles. Consider: /-3-> D A -1-> B -1-> C \------4------^ In this case, the longest path i

That doesn't actually work, because a DAG only lacks directed cycles. Consider: /-3-> D A -1-> B -1-> C \------4------^ In this case, the longest path is A-C, but C will be held at level 2 by B, leaving D lowest at level 3. This works for a fully-acyclic directed graph (eg a tree), but not for a directed-acyclic directed graph. It can also find the node whose shortest path is the longest (so longest shortest path, minimax style). (It also works for a acyclic undirected graph, as illustrated at [0], but that's a bit tangential.) 0: https://www.youtube.com/watch?v=wGrOPSBPpyk https://www.youtube.com/watch?v=wGrOPSBPpyk