PT07Z  Longest path in a tree
You are given an unweighted, undirected tree. Write a program to output the length of the longest path (from one node to another) in that tree. The length of a path in this case is number of edges we traverse from source to destination.
Input
The first line of the input file contains one integer N  number of nodes in the tree (0 < N <= 10000). Next N1 lines contain N1 edges of that tree  Each line contains a pair (u, v) means there is an edge between node u and node v (1 <= u, v <= N).
Output
Print the length of the longest path on one line.
Example
Input: 3 1 2 2 3 Output: 2
hide comments
Rajat Gautam:
20170518 23:09:07
@prashant2018 Use first bfs to find farthest node. and second bfs starting from this node to find longest path. 

helloitsme:
20170503 21:36:54
I used bfs twice with adjacency list in JAVA ,then tried dfs twice but still its timing out :( , Please help! 

rohit9934:
20170502 07:23:45
Damn man,so many tries. I used double BFS, 1 for finding arbitrary farthest node and other from finding farthest node from that node. 

prashant2018:
20170420 23:23:15
getting WA on 4th test case. Can someone help please. Using double bfs Last edit: 20170421 11:02:31 

gulsntils_12:
20170419 12:50:51
A reminder  the answer is not the number of nodes in the path but the number of edges in it.


ydeepak1889:
20170311 15:08:43
AC in one Go! Single dfs 

prasoonbatham:
20170305 19:41:38
Easy two DFS :) 

kingp:
20170303 09:43:30
is there any need for bfs in a tree there is only one path between any two vertices so dfs is enough. 

da_201501181:
20170302 21:45:52
AC in one Go! Simple double dfs 

gboduljak:
20170215 22:24:33
should be moved to tutorial 
Added by:  ThanhVy Hua 
Date:  20070328 
Time limit:  0.5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  Coauthor Amber 