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
little_finger:
20190116 20:56:14
AC in one go


bradyawn:
20181211 21:49:28
The solution from @ktcoder is the easiest and easier to generalize to harder problems. 

alishahali1382:
20181129 12:00:59
don't say the solution here!


jagadishsagi:
20180921 20:07:56
Very simple solved using bfs twice 0.01s 

saketag007:
20180902 22:10:56
AC in one go , very simple apply 2 BFS. 

jyotiradityafc:
20180815 18:07:56
@suvro_coder it is because n = 6, hence edges should be 5 but you provided 6 edges. Put n = 7 and you will get your answer. 

soumi_1987:
20180804 10:37:08
For Java use BufferedReader for I/O rather than Scanner. 

suvro_coder:
20180720 11:00:53
Weak Test Cases:


markomafko972:
20180719 17:44:37
Try CLCKBAIT after this! 

vivek_dwivedi:
20180706 05:52:41
those who are doing it by finding it longest and second longest .! how are you guys are substracting extra value that you have counted ! (considering your dfs does not start from any root)! 
Added by:  ThanhVy Hua 
Date:  20070328 
Time limit:  0.181s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  Coauthor Amber 