Sphere Online Judge

SPOJ Problem Set (classical)

1436. Is it a tree

Problem code: PT07Y

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


Added by:Thanh-Vy Hua
Time limit:0.166s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel Pentium G860 3GHz)
Languages:All except: ERL JS
Resource:Co-author Amber

hide comments
2014-08-06 16:37:56 mohsin mohammad
My first graph problem AC in first attempt
really exciting........
2014-07-30 05:04:12 Vignesh
I second dragonemporer. I aced with failing to build a proper graph.
2014-07-25 12:55:37 Hammad Akhtar
easy one.
No need of dfs.
Mem - 1.6M TIME - 0.00S
2014-07-20 09:05:12 Navneet M Kumar
Can someone provide some test cases ?
I am getting a wa
2014-07-18 12:22:32 Naruto uzumaki
first graph problem ever :)
2014-07-09 11:45:30 Shireen Nagdive
Can anyone give hints how to solve the code without dfs and bfs?
2014-07-05 16:20:30 chin
getting seg fault..:(
Finally got AC..:D..got my mistake..

Last edit: 2014-07-07 04:56:16
2014-06-11 10:14:08 Manu Narsaria
Submission ID:11738679
Please check it satisfies all possble input that i could find....
2014-05-26 06:40:47 dragonemperor
Weak test case. In none of the cases, number of edges is less than number of vertices. I have a condition that checks if number of edges is less than number of vertices minus 1. If it satisfies, my code is not taking edges as input but I still got AC.
2014-05-20 22:09:10 Suraj Rajan
cycles and connectedness..!! :)
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