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
wiseman_123:
20210224 19:19:39
time  O(N).


wille_25:
20201230 13:17:44
AC in one GO


kapilsukrit2:
20200922 10:12:46
just use the diameter of a tree concept. you're good to go then! 

sabbir0152:
20200911 18:39:20
Last edit: 20200911 19:00:54 

sabbir0152:
20200911 17:49:08
this is a problem of ....finding diameter of tree


lm10_piyush:
20200802 22:56:09
AC in one go, dp on trees. 

amitk766:
20200707 15:56:58
Run dfs/bfs two times , in the first run find the farthest vertex from vert 1, and the again run dfs from that vertex(farthest) and calculate the longest path. 

sarveshjain967:
20200625 13:37:47
AC in one go. Remember what constitutes the longest path:


zegatron:
20200622 20:37:33
Do not print a new line at the end of the ans. 

zegatron:
20200622 20:35:21
I am getting wrong answer on my code. I call bfs for each node. and take the maximum depth. 
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 