PT07Y  Is it a tree
You are given an unweighted, undirected graph. Write a program to check if it's a tree topology.
Input
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).
Output
Print YES if the given graph is a tree, otherwise print NO.
Example
Input: 3 2 1 2 2 3 Output: YES
hide comments
karthik1997:
20151121 14:23:58
For people


garmel:
20151113 21:27:43
I think if you aren't confortable with graphs, you should search for a solution and understand it by using the handexecution on a paper... 

archit saxena:
20151111 09:42:47
can the name of nodes be fractions


dk619:
20151102 23:21:16
Disjoint set data structures is the best


dragonemperor:
20151021 12:07:39
Union find got AC. At first I set parent of each node as 1. This got TLE. Setting parent[a]=a worked like a charm 

Vaibhav Malik:
20151006 20:54:26
AC in one GO :) 

jarvis:
20150928 23:37:35
First graph :) first DFS :) love it <3 after 5 WA


Sarthak Munshi:
20150925 14:29:21
Check :


[Mayank Pratap]:
20150922 14:16:28
Enjoyed this problem... :)


jyotman94:
20150919 21:03:46
First Graph Problem :) AC 
Added by:  ThanhVy Hua 
Date:  20070328 
Time limit:  0.5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO 
Resource:  Coauthor Amber 