学步园

Background 
Professor Hopper is researching the sexual behavior of a rare species of bugs. He assumes that they feature two different genders and that they only interact with bugs of the opposite gender. In his experiment, individual bugs and their interactions were easy
to identify, because numbers were printed on their backs. 
Problem 
Given a list of bug interactions, decide whether the experiment supports his assumption of two genders with no homosexual bugs or if it contains some bug interactions that falsify it.

The first line of the input contains the number of scenarios. Each scenario starts with one line giving the number of bugs (at least one, and up to 2000) and the number of interactions (up to 1000000) separated by a single space. In the following lines, each
interaction is given in the form of two distinct bug numbers separated by a single space. Bugs are numbered consecutively starting from one.

The output for every scenario is a line containing "Scenario #i:", where i is the number of the scenario starting at 1, followed by one line saying either "No suspicious bugs found!" if the experiment is consistent with his assumption about the bugs' sexual
behavior, or "Suspicious bugs found!" if Professor Hopper's assumption is definitely wrong.

2
3 3
1 2
2 3
1 3
4 2
1 2
3 4

Scenario #1:
Suspicious bugs found!

Scenario #2:
No suspicious bugs found!

Huge input,scanf is recommended.

TUD Programming Contest 2005, Darmstadt, Germany

这道属于并查集啊，种类并查集，通过设一个关系数组，标记它的类别，并在找父亲的时候不断更新关系

#include<iostream>
#include<cstdio>
using namespace std;
int n,m,f[2001],r[2001],ans,num;
int a,b;
int find(int i)
{
    if(f[i]==i)return i;
    int t=f[i];
    f[i]=find(f[i]);
    r[i]=(r[i]+r[t]+1)%2;
    return f[i];
}
void un(int a,int b)
{
    int x=find(a);
    int y=find(b);
    f[x]=y;
    r[x]=(r[b]-r[a])%2;
}
int main()
{
    num=1;
    int t;
    scanf("%d",&t);
    while(t--)
    {
        ans=0;
        scanf("%d%d",&n,&m);
        for(int i=1;i<=n;i++)
        {
            f[i]=i;
            r[i]=1;
        }
        for(int i=0;i<m;i++)
        {
            scanf("%d%d",&a,&b);
            if(find(a)==find(b))
            {
                if(r[a]==r[b])ans=1;
            }
            else
            {
                un(a,b);
            }
        }
        if(ans)cout<<"Scenario #"<<num++<<":"<<endl<<"Suspicious bugs found!"<<endl;
        else cout<<"Scenario #"<<num++<<":"<<endl<<"No suspicious bugs found!"<<endl;
        cout<<endl;
    }
    return 0;
}