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
zoso_floyd:
20200415 14:42:57
Apply bfs two times. https://www.geeksforgeeks.org/longestpathundirectedtree/ should help. 

aditya_shukla:
20200330 14:26:15
Avoid using Scanner class in Java for taking input. 

blackhat_130:
20200326 00:09:01
Beginner level problem for those who want to learn dfs.


unafraidofdog:
20200210 05:25:13
Last edit: 20200210 07:06:16 

bohot_hard_123:
20191223 03:31:46
also many many thanks to @ jame_boy to sharing further in comment box


emtiaz_001:
20191220 16:17:36
the moral of the story is to find the root correctly and calculate the distance from the rooooooooottttttttttt........ 

rmcr714:
20191126 15:30:20
is it a tree problem because there is cycle present like 1 2 2 3, or do i need to learn graph for this 

hetp111:
20191112 09:40:11
easier then it looks... calc height of each node. then for every node find 2 child with largest height. 

ishancosmos25:
20191013 02:08:53
https://discuss.codechef.com/t/longestpathinatreeusingdfsanddoublebfs/8893 for reference..


scolar_fuad:
20190904 06:04:59
Simple dfs problem ...

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 