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 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

hide comments
vedang: 2015-12-25 18:23:38

Don't know why but when I changed memset to fill_n in my C++ code, WA turned into AC!

the_sage: 2015-12-18 11:30:44

the tree should not have a cycle but the test cases have a cycle in them for example
7
1 2
2 3
4 5
5 6
6 7
5 7

the_sage: 2015-12-18 11:18:19

for the test case
7
1 2
2 3
4 5
5 6
6 7
5 7
this is not a tree because it has a cycle... then how its a valid question

codelover25: 2015-12-17 16:36:48

AC in 1 go :) Just be careful with ordering of tree.

piyush9620: 2015-12-15 11:20:08

http://www.spoj.com/users/markroxor
ur example is not a connected graph

maverick_10: 2015-12-13 11:59:00

Ooh, finally I am learnig graphs!!!
did with both dfs and bfs

bunnycoder: 2015-12-12 08:42:09

Be careful with the line one node to another costed me 1 WA simple dfs

Shantanu Banerjee: 2015-12-02 09:20:10

@Mohit Rathore The input will not be a forest.
Read the Input Section carefully. :) Only 1 tree will be there

Akshay Damle: 2015-10-27 23:14:53

AC in 1 go :) This Quora answer was helpful: https://www.quora.com/How-does-following-algorithm-for-finding-longest-path-in-tree-work

satish9040: 2015-10-27 15:06:14

http://apps.topcoder.com/forums/?module=Thread&threadID=794604&start=0&mc=3#1758019


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