PT07Y - Is it a tree

You are given an unweighted, undirected graph. Write a program to check if it's a tree topology.


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).


Print YES if the given graph is a tree, otherwise print NO.


3 2
1 2
2 3


hide comments
selva1996: 2018-06-08 10:00:24

No need DFS or DSU just a visited array works....

anushka_ahuja: 2018-06-05 13:32:30

Use #DSU AC in one go!!!!

code0monkey1: 2018-04-06 17:31:22

DSU makes this super easy . #beware ( tot edges = tot nodes -1 , in a valid tree )

lefthander: 2018-04-01 05:38:46

AC in one go ! Only DFS 0.00sec

sanjeev: 2018-03-28 18:34:38

solve it with dsu algorithm, you will get to know few things.

ameyanator: 2018-03-19 06:57:59

Solved using BFS. Conditions to keep in mind are that n==m-1 for a tree. And whenever this holds true all the nodes must be connected so simply bfs :)

naduhrin78: 2018-02-04 05:35:59

DSU yolo

himansh242: 2018-02-01 15:35:12

0.01 ac!! :)

coding_panda: 2018-01-29 02:54:21

Killed in one go ! Disjoint Set all the way !

bradyawn: 2018-01-23 20:06:24


dsu is much easier then dfs smh

Added by:Thanh-Vy Hua
Time limit:0.5s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO
Resource:Co-author Amber