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.


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).


Print the length of the longest path on one line.


1 2
2 3


hide comments
zoso_floyd: 2020-04-15 14:42:57

Apply bfs two times. should help.

aditya_shukla: 2020-03-30 14:26:15

Avoid using Scanner class in Java for taking input.

blackhat_130: 2020-03-26 00:09:01

Beginner level problem for those who want to learn dfs.
Gives me a bit of confidence.

unafraidofdog: 2020-02-10 05:25:13

Last edit: 2020-02-10 07:06:16
bohot_hard_123: 2019-12-23 03:31:46

also many many thanks to @ jame_boy to sharing further in comment box
it took me 1 day to come up with solution a very helpful video

Last edit: 2019-12-23 03:32:10
emtiaz_001: 2019-12-20 16:17:36

the moral of the story is to find the root correctly and calculate the distance from the rooooooooottttttttttt........

rmcr714: 2019-11-26 15:30:20

is it a tree problem because there is cycle present like 1 2 2 3, or do i need to learn graph for this

hetp111: 2019-11-12 09:40:11

easier then it looks... calc height of each node. then for every node find 2 child with largest height.

ishancosmos25: 2019-10-13 02:08:53 for reference..

scolar_fuad: 2019-09-04 06:04:59

Simple dfs problem ...
easy one for beginner...

Happy coding

Added by:Thanh-Vy Hua
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