SPOJ.com - Problem PT07Z

PT07Z - Longest path in a tree

#dfs

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 N-1 lines contain N-1 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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	rockstar_786: 2019-07-05 22:15:49 @sarthak_1998 bro i was getting the same its due to small memory allocation of declared array. You are doing a mistake like this : ----> int arr[2000][2000]; int a = arr[2001] [2000]; You can read one of the answers here. https://www.quora.com/Why-am-I-getting-a-runtime-error-SIGSEGV-when-I-submit-my-solution-on-CodeChef-or-Sphere-Online-Judge-SPOJ-while-its-working-fine-and-even-giving-the-correct-output-on-my-system
	an09mous: 2019-07-03 12:12:10 We can precompute heights of all the sub-trees in an array for faster computation
	shahayush457: 2019-07-02 09:37:56 Just use 2 dfs :)
	sarthak_1998: 2019-06-26 17:26:59 My code is giving runtime error (SIGSEGV) however it is giving right answer on every test case I tried. Please, someone, help me. https://ideone.com/8T1dch
	anand_undavia: 2019-06-15 19:27:03 This helped me a lot: https://www.youtube.com/watch?v=w9vjFB7m0PM Also, SPOJtoolkit has really nice test cases for this problem -- apart from well, the first test case.
	cenation007: 2019-06-03 17:01:17 take any node as root, start with root to find longest path and the rest is dfs AC in one go:) Last edit: 2019-06-03 17:01:56
	arunkumarreddy: 2019-06-02 20:16:54 i have submitted solutions for 2 problems on graphs today. I got NZEC error for both the problems, can someone help me understand why i am getting that error. If you want i can share my code with you.
	klmo: 2019-04-25 15:38:38 1 DFS. finally ac in java.
	klmo: 2019-04-25 13:45:49 2 dfs operation with tree in adjacency matrix is giving TLE in java. Using BufferedReader. Any suggestion?
	brijraj: 2019-02-17 11:54:05 @suvro_coder your input is wrong. There are 7 nodes instead of 6. Otherwise it will not add edge from 6 to 7

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Added by:	Thanh-Vy Hua
Date:	2007-03-28
Time limit:	0.5s
Source limit:	50000B
Memory limit:	1536MB
Cluster:	Cube (Intel G860)
Languages:	All except: ERL JS-RHINO NODEJS PERL6 VB.NET
Resource:	Co-author Amber