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
maruf_robin:
20180120 18:53:07
Keep in mind a tree must have n1 edges & all the node will be connected. 

anurag_05:
20180115 14:30:56
AC in one go... just check for cycles and whether each and every vertex is visited during DFS


aishu7:
20171227 20:43:22
Adjacency list and dfs would work


nixys:
20171216 15:23:56
AC in one Go!!! 

sayasaiteja:
20171212 15:58:49
AC in one GO!!


abhar10:
20171114 08:15:54
My 50th!!


punee901:
20171026 14:36:12
java people use input method other than scanner class it gives me one tle.


g_o_d:
20171022 10:24:57
It can also also be solved as follow:


vicky_1998:
20171019 13:02:25
Just Disjoint Set works quite well 

hemant1612:
20171003 17:53:33
cool problem 
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 