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
vengatesh15: 2016-12-10 14:08:03

Simple DFS

vishal_khanna: 2016-12-04 15:41:18

I'm getting WA for test 6. How do I know if my code is correct or not?

nimmumanoj: 2016-12-04 10:46:42

So easy. You don't have to use map. The nodes are numbered from 1 to N.

syed_tanveer: 2016-11-26 09:56:23

My 50th, did it using union-find.

reconnect: 2016-11-24 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: 2016-11-24 23:19:10
adhyyan: 2016-11-02 17:08:14

Use the fact that any tree will have N - 1 edges

code_aim: 2016-10-16 15:58:39

Last edit: 2016-10-16 16:53:56
joe001: 2016-10-07 14:03:55

Cycle detection using DFS ! :-)

aahmedsamy: 2016-10-03 07:18:47

cau you explain the problem please :)

lalrishav: 2016-08-28 14:59:16

why getting wrong answer on test 6


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