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
harry_shit:
20200818 13:53:43
simple dfs will do the the work 

saurabh_shinde:
20200814 16:34:59
AC in one go!! Thanks to comment on connected component 

adikrmishra_1:
20200622 19:19:21
simple one using


picchi_67:
20200613 09:10:43
easy DSU problem...but you have to know what is tree...


afaiyaz:
20200611 12:44:01
If anyone getting TLE using recursive dfs just pass the vector to dfs function as a const reference.(in c++ ofcourse) Last edit: 20200611 12:44:44 

soumen_1696:
20200425 20:05:26
The main thing to remember to check weather tree >


yourmom__:
20200421 07:30:05
I heard people say that in java, Scanner is causing TLE. It's not true, as mine got accepted using Scanner. I used BFS. 

samio:
20200420 08:43:14
@sangmai, no it doesn't give TLE for recursive DFS. 

zoso_floyd:
20200415 09:43:55
Check if no_of_connected_components==1 && no_of_edges==N1; 

abhigurjeet:
20200319 11:17:03
learnt depth first search using adjacent list

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 