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
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Himanshu Sharma:
20160814 03:12:59
single dfs, my 50th ;[] 

Surbhi:
20160807 17:31:32
Why is adjacency matrix not working? 

saurabh789:
20160711 13:10:07
use dfs two times first time to find a node "s" which is at max distance from any child node, next time use "s" as starting node and find length of longest path 

sumit suthar:
20160707 14:51:28
double dfs easy one.. 

Suryansh Agnihotri:
20160701 12:28:32
It is having weak test cases , one of my wrong solution got accepted. 

ajay_raj:
20160629 19:44:23
Last edit: 20160701 03:48:57 

kunal todi:
20160625 11:56:21
Can anyone help me.I got TLE..it runs till 5th test case... 

pratika:
20160624 11:57:17
WA repeatedly, removed memset and got ac :O 

baadshah_:
20160622 21:11:56
Finally AC ! did it using single DFS!!dont use matrix !!USE adj List Last edit: 20160622 21:13:15 

demigod_luffy:
20160618 09:00:36
My 50th one!!! one dfs + dp :) 
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 