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
avx_5801: 2021-07-14 10:41:58

AC in One Go ...by using just 2 dfs call one call for finding farthest node and other for finding longest distances using farthest node :)

darkdeveloper: 2021-07-07 20:03:48

The question is highly misleading i tried a lot of times the actual number of nodes is greater than 10000. I took an array of 1e6 for the solution to finally get accepted. If your code fails at test(5) take the size of array to be 1e6 (1000000)

loser_404: 2021-06-04 08:15:42

useful lecture https://www.youtube.com/watch?v=JahlIiTzZWQ&t=947s&ab_channel=HiteshTripathiHiteshTripathi

adi123cm: 2021-06-02 03:49:54

use double dfs

adi123cm: 2021-06-02 03:49:29

good question helped clear my concepts.

lolkey: 2021-04-20 18:04:44

AC in one GO :)

Trivial centroid decomposition problem

Last edit: 2021-04-20 18:15:00
rushi2001: 2021-04-09 21:24:19

@wiseman_123 - How can you say that space is O(1)
What about visited array and adjacency list ?

wiseman_123: 2021-02-24 19:19:39

time - O(N).
Space - O(1).

wille_25: 2020-12-30 13:17:44

AC in one GO
double BFS (0.01s) :)

Last edit: 2020-12-30 13:18:06
kapilsukrit2: 2020-09-22 10:12:46

just use the diameter of a tree concept. you're good to go then!


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