Finding the longest cycle in a directed graph using DFS

Question

I need to find the longest cycle in a directed graph using DFS.

I once saw this Wikipedia article describing the way of doing this, and I think it approached the pro

Answer 1

I think that longest elementary cycle (or circuit) is better terminology than longest cycle.

Anyway, this pdf may be helpful: Finding All the Elementary Circuits of a Directed Graph

This one year old stackoverflow question has also many links to related problems and algorithms: Finding all cycles in a directed graph