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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
| Added by: | Thanh-Vy Hua |
| Date: | 2007-03-28 |
| Time limit: | 0.5s |
| Source limit: | 50000B |
| Memory limit: | 1536MB |
| Cluster: | Cube (Intel G860) |
| Languages: | All except: ERL JS-RHINO |
| Resource: | Co-author Amber |
hide comments
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2020-02-18 11:58:55
2 5 7 0 0 0 0 0 0 0 0 3 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 5 15 0 0 0 0 2 0 2 0 0 0 0 1 2 0 1 0 0 0 1 0 2 0 2 2 0 1 2 0 0 0 2 1 0 2 0 1 0 2 0 0 0 0 0 0 0 0 0 0 1 0 2 0 0 1 2 0 0 2 0 0 0 2 1 0 2 0 0 0 0 0 3 0 0 0 0 Last edit: 2020-02-18 12:00:01 |
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2020-02-06 16:14:54
SImple AC: Check if connected components = 1 & nodes - 1 = edges. |
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2020-01-16 11:57:27
dfs with recursion gets TLE, use queue instead |
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2019-12-30 23:00:07
Just think about it conceptually. What is a tree? A tree is a connected undirected acyclic graph. Connected -> all vertices must be connected to at least one other vertex Undirected -> an edge points in both directions (u,v) and (v,u) Acyclic -> (a <-> b <-> c) Not Acyclic (a <-> b <-> c <-> a) = Bad |
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2019-12-30 16:38:25
AC if n==no. of times dfs runs && n==m+1 YES |
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2019-11-05 11:46:00
Can someone plzz tell me answer of this case and why 6 5 1 4 2 4 3 4 5 4 5 6 |
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2019-09-23 08:40:58
use union-find much better for this problem |
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2019-08-21 07:55:05
HINT: Any connected graph G with n vertices and (n-1) edges is a tree (No need to search for cycles, only connection) Last edit: 2019-08-21 07:56:17 |
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2019-08-17 08:05:37
The tree may not be a binary tree. A node may have more than 3 childs |
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2019-07-20 19:35:16
AC only if one considers it as directed Graph. Last edit: 2019-07-20 19:36:10 |
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