From Algorithm Wiki
Revision as of 05:48, 31 January 2016 by Rahul Biswas
use dfs to find cycle of lenght 3.
we maintain an array parent[i].
while processing any backedge u-v we check whether gradparent of u is equal to v .if true we found a cycle of lenght 3.
i,e parent[parent[u]] == v,then found cycle of lenght 3