POJ 2492-A Bug's Life（帶權並查集）

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

#include<iostream>
#include<cstdio>
#include<iomanip>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<map>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;
#define INF 0xfffffff
#define MAXN 10010
int fa[MAXN];
int a[MAXN],b[MAXN];
bool rel[MAXN];//0/1標記和樹根的同異性關係
int setfind(int x)
{
    int temp=fa[x];
    if(temp==x) return x;
    fa[x]=setfind(temp);
    rel[x]=(rel[x]+rel[temp])%2;//更新同異性關係
    return fa[x];
}

void join(int p,int q)
{
    int x=setfind(p);
    int y=setfind(q);
    if(x!=y) fa[x]=y;
    rel[x]=((rel[p]-rel[q]+1)%2);//確定同異性關係，如果之前是同性則改為異性
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("G:/cbx/read.txt","r",stdin);
    //freopen("G:/cbx/out.txt","w",stdout);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t,ca=0;
    cin>>t;
    while(t--)
    {
        for(int i=0; i<MAXN; ++i) fa[i]=i;
        memset(rel,false,sizeof(rel));
        int n,m;
        bool flag=false;
        cin>>n>>m;
        for(int i=0; i<m; ++i)
        {
            int a,b;
            cin>>a>>b;
            if(setfind(a)==setfind(b))
            {
                if(rel[a]==rel[b]%2)
                    flag=true;//出現同性戀
            }
            else join(a,b);
        }
        if(flag) cout<<"Scenario #"<<++ca<<":"<<endl<<"Suspicious bugs found!"<<endl<<endl;
        else cout<<"Scenario #"<<++ca<<":"<<endl<<"No suspicious bugs found!"<<endl<<endl;
    }
    return 0;
}