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
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,

rohit9934: 2017-02-13 17:15:02

4 hours in front of PC,2 hours of testing,1 hour of No and then Green Tick <3 .

programminator: 2017-02-13 09:08:47

beautiful solution using union-find

cipher_097: 2017-02-12 13:57:13

Weak test cases. Admin, please check the test cases once again.

Last edit: 2017-02-12 13:57:37
cake_is_a_lie: 2017-02-10 17:45:00

IMO it's easier to code using union-find than BFS/DFS, since you don't even need to keep the edges in memory.

soodan: 2016-12-23 07:28:04

Spoilers:
1.Graph should be connected.
2.No of cycles in graph == 0.
3.No of edges == No of nodes - 1.
Note : Use adjacency list and **STL .


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