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
syamphanindra: 2017-05-23 18:27:35

Take care to check all nodes are visited or not it gave me 3 WA so check it

Rajat Gautam: 2017-05-20 00:29:49

Used BFS once , if no. of edges is less than no. of vertex. And any one or more than one node remained unvisited after BFS then there is a cycle for sure because then there will be n-1 edges and n-1 vertex and 1 vertex separated.

bluelegend: 2017-05-18 09:38:34

same code accepted in C but TLE with C++(14) :p
execution time 0.00 sec

Last edit: 2017-05-18 09:42:29
piyushbharti: 2017-05-18 08:26:49

same question ac on codechef but wa on spoj ... can anyone explain why.. if code is needed... I will supply

stiffler22: 2017-05-05 09:40:39

weak testcases, my code gives NO for
3 2
2 1
3 1
but still got AC

the_phoenixx: 2017-04-21 15:53:35

Easy-One I just use Union set!!
thatsit...

InjarapuBalaSatishKumar: 2017-04-16 12:08:29

I used union-find algorithm to check whether graph contains cycle/not. I was getting TLE. Same code if I submit in codechef it's got accepted.
Correct Answer
Execution Time: 0.04
Help me why my code is not accepted by spoj!!
This is my code:
<Don't post any source code here.>

Last edit: 2017-04-17 04:17:51
subhamsandilya: 2017-03-08 20:06:18

nice problem..

da_201501181: 2017-03-02 22:39:23

AC in one GO!! Easy used union-find..!!

gboduljak: 2017-02-25 21:50:09

should be moved to tutorial,


Added by:Thanh-Vy Hua
Date:2007-03-28
Time limit:0.166s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO
Resource:Co-author Amber