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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	hetp111: 2019-08-24 05:04:07 2 dfs: Start from any node and find the farthest node (say x), now again do a dfs from x and find the farthest node (say y), the answer is distance between x and y. Last edit: 2019-08-24 05:04:21
	sonianand966: 2019-08-21 15:08:26 Did it using 2-bfs method however was a difficult one as an all new question!
	elzahaby: 2019-08-14 22:05:54 using 2 BFS can't do it with DFS acctually idk why xD
	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 :)
	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.
	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?

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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