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
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vengatesh15:
20161210 14:08:03
Simple DFS


vishal_khanna:
20161204 15:41:18
I'm getting WA for test 6. How do I know if my code is correct or not? 

nimmumanoj:
20161204 10:46:42
So easy. You don't have to use map. The nodes are numbered from 1 to N. 

syed_tanveer:
20161126 09:56:23
My 50th, did it using unionfind. 

reconnect:
20161124 23:17:50
i am getting a TLE. I am using BFS . Can anybody please suggest the error. Is this because of the adjacency matrix? Last edit: 20161124 23:19:10 

adhyyan:
20161102 17:08:14
Use the fact that any tree will have N  1 edges 

code_aim:
20161016 15:58:39
Last edit: 20161016 16:53:56 

joe001:
20161007 14:03:55
Cycle detection using DFS ! :) 

aahmedsamy:
20161003 07:18:47
cau you explain the problem please :)


lalrishav:
20160828 14:59:16
why getting wrong answer on test 6 
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 