Sphere Online Judge

SPOJ Problem Set (classical)

1436. Is it a tree

Problem code: PT07Y

You are given an unweighted, undirected graph. Write a program to check if it's a tree topology.


The first line of the input file contains two integers N and M --- number of nodes and number of edges in the graph (0 < N <= 10000, 0 <= M <= 20000). Next M lines contain M edges of that graph --- Each line contains a pair (u, v) means there is an edge between node u and node v (1 <= u,v <= N).


Print YES if the given graph is a tree, otherwise print NO.


3 2
1 2
2 3


Added by:Thanh-Vy Hua
Time limit:0.166s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel Pentium G860 3GHz)
Languages:All except: ERL JS SCM chicken
Resource:Co-author Amber

hide comments
2014-08-22 08:07:26 do_do
union-find algorithm worked... :)
2014-08-16 01:59:11 anand pandey

Last edit: 2014-08-16 14:30:58
2014-08-16 01:58:44 anand pandey
[code removed by cyclops; see notes below, "1. Don't post any source code here."]

Last edit: 2014-08-16 04:21:23
2014-08-15 18:39:13 Naruto uzumaki
@jarvis this is a tree,
2014-08-12 20:40:11 Miroslav Kovar
Please, what are some tricky test cases? I am getting WA, although the algorithm works fine for everything I come up with...
2014-08-10 00:50:28 .:: Jarv1s ::.
4 3
1 2
2 3
2 4

is giving YES for AC solution, is it correct? Admin please rejudge all solutions...
2014-08-06 16:37:56 mohsin mohammad
My first graph problem AC in first attempt
really exciting........
2014-07-30 05:04:12 Vignesh
I second dragonemporer. I aced with failing to build a proper graph.
2014-07-25 12:55:37 Hammad Akhtar
easy one.
No need of dfs.
Mem - 1.6M TIME - 0.00S
2014-07-20 09:05:12 Navneet M Kumar
Can someone provide some test cases ?
I am getting a wa
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