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


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saketag007: 2018-09-02 22:10:56

AC in one go , very simple apply 2 BFS.

jyotiradityafc: 2018-08-15 18:07:56

@suvro_coder it is because n = 6, hence edges should be 5 but you provided 6 edges. Put n = 7 and you will get your answer.

soumi_1987: 2018-08-04 10:37:08

For Java use BufferedReader for I/O rather than Scanner.

suvro_coder: 2018-07-20 11:00:53

Weak Test Cases:
1 2
2 3
3 4
2 5
2 6
6 7

In this test case output should be 4, (4-3-2-6-7) but my accepted solution gives output 3.
Done in 1 dfs.

markomafko972: 2018-07-19 17:44:37

Try CLCKBAIT after this!

vivek_dwivedi: 2018-07-06 05:52:41

those who are doing it by finding it longest and second longest .! how are you guys are substracting extra value that you have counted ! (considering your dfs does not start from any root)!

ktcoder: 2018-06-22 11:39:54

It just requires single dfs.
Just add the longest and 2nd longest path from the source node.

dikshit_30: 2018-06-19 18:31:02

Logic: Use two bfs. The first to find the farthest node from a particular node. That will be the leaf node. Again applying bfs on this will give you the maximum distance.

shivamgarg1901: 2018-05-25 11:00:13

If your approach is correct you not need to worry about the root of the tree.
Accepted in a Go!

yaswanth desu: 2018-04-10 04:45:17

If any one having doubt regarding the root means, consider the below example
1 2
2 3

Here 1 is the root.

1 2
2 3
4 1

Here 4 is the root.

Added by:Thanh-Vy Hua
Time limit:0.5s
Source limit:50000B
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