FZU 2141 Sub-Bipartite Graph

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原文链接：http://www.cnblogs.com/cyd308/p/4771425.html

本文探讨了一种从给定简单无向图中选择至少一半边长的子双部分图的方法，详细介绍了算法实现及实例解析。

Sub-Bipartite Graph

Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%I64d & %I64u

Submit Status Practice FZU 2141

Description

Given a simple undirected graph G with n vertices and m edges, your task is to select a sub-bipartite graph of G with at least m/2 edges.

In the mathematical field of graph theory, a bipartite graph (or bigraph) is a graph whose vertices can be divided into two disjoint sets U and V such that every edge connects a vertex in U to one in V; that is, U and V are each independent sets. Equivalently, a bipartite graph is a graph that does not contain any odd-length cycles.

Equivalently, a bipartite graph is a graph that does not contain any odd-length cycles.

In the mathematical field of graph theory, a subgraph is a graph G whose graph vertices and graph edges form subsets of the graph vertices and graph edges of a given graph G..

In graph theory, a simple graph is a graph containing no self-loops or multiple edges.

from wikipedia

Input

The first line of the date is an integer T, which is the number of the text cases.

Then T cases follow, each case starts of two numbers N and M, representing the number of vertices and the number of edges, then M lines follow. Each line contains two integers x and y, means that there is an edge connected x and y. The number of nodes is from 1 to N.

1 <= T <= 100, 1 <= N <= 100, 0 <= M <= 10086

Output

For each case, you should output two lines to describe your sub-graph, the first line is the set of U and the second line is the set of V.

Each line should output an integer F first, which is the total number of the vertices in this set, then F integers follow which are the number of each vertex of this part, see sample input and sample output for more details.

You can assume that the answer is always existed.

Sample Input

3 1 0 2 1 1 2 3 3 1 2 2 3 1 3

Sample Output

1 1 0 1 1 1 2 2 1 2 1 3

Hint

This problem is special judge.

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <algorithm>
 4 using namespace std;
 5 
 6 int g[110][110],color[110],B,W;
 7 
 8 int cal(int p)
 9 {
10     int b=0,w=0;
11     int i;
12     color[p]=1;
13     for(i=1;i<p;++i)
14         if(g[i][p] && color[i]!=color[p]) b++;
15     color[p]=2;
16     for(i=1;i<p;++i)
17         if(g[i][p] && color[i]!=color[p]) w++;
18     if(b>w) color[p]=1,B++;
19     else color[p]=2,W++;
20 }
21 
22 int main()
23 {
24     int T,n,m;
25     scanf("%d",&T);
26     while(T--)
27     {
28         int i,j;
29         scanf("%d%d",&n,&m);
30         memset(color,0,sizeof(color));
31         memset(g,0,sizeof(g));
32         int u,v;
33         for(i=1;i<=m;++i)
34         {
35             scanf("%d%d",&u,&v);
36             g[u][v]=1;
37             g[v][u]=1;
38         }
39         
40         B=W=0;
41         for(i=1;i<=n;++i)
42             cal(i);
43         printf("%d",B);
44         for(i=1;i<=n;++i)
45             if(color[i]==1) printf(" %d",i);
46         printf("\n");
47         printf("%d",W);
48         for(i=1;i<=n;++i)
49             if(color[i]==2) printf(" %d",i);
50         printf("\n");
51     }
52     return 0;
53 }