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
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!

sabbir0152: 2020-09-11 18:39:20

Last edit: 2020-09-11 19:00:54
sabbir0152: 2020-09-11 17:49:08

this is a problem of ....finding diameter of tree

lm10_piyush: 2020-08-02 22:56:09

AC in one go, dp on trees.

amitk766: 2020-07-07 15:56:58

Run dfs/bfs two times , in the first run find the farthest vertex from vert 1, and the again run dfs from that vertex(farthest) and calculate the longest path.

sarveshjain967: 2020-06-25 13:37:47

AC in one go. Remember what constitutes the longest path:
1. One more than the longest path below the node
2. largest ever = max("two long paths below the node", largest ever)


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