Diameter_of_Undirected_graph.md

Solution:

start at an arbitrary node and find the farthest node from it let’s call it FN (use dfs/bfs).
Now from FA find the farthest node.. this will give you the diameter of the undirected graph

Why does the above approach work ?

In a tree, the diameter is always the longest path between two nodes.
Starting from any arbitrary node, the farthest node from it will always be one endpoint of the diameter.
From that endpoint, the farthest node will be the other endpoint of the diameter.

This approach runs in O(V + E) time since it involves two traversals of the tree.