POJ 2492

 #include<iostream>
 #include<stdio.h>
 #define MAXN 2050
 using namespace std;

 int pre[MAXN];
 int opp[MAXN];

 void init(int n)
 {
     int i;
     for(i = ; i <= n; ++ i)
     {
         pre[i] = i;
         opp[i] = -;
     }
 }

 int find_pre(int x)
 {
     if(pre[x] != x)
     {
         pre[x] = find_pre(pre[x]);
     }
     return pre[x];
 }

 int comb(int x,int y)
 {
     if(x == -)
         return y;
     if(y == -)
         return x;
     pre[x] = y;
     return y;
 }

 int main()
 {
     //freopen("acm.acm","r",stdin);
     int test;
     int n;
     int m;
     int i;
     int u;
     int v;
     int temp1;
     int temp2;
     bool boo;
     bool bo;
     int k;
     scanf("%d",&test);
     for(k = ; k < test; ++ k)
     {
         scanf("%d%d",&n,&m);
         init(n);
         boo = false;

         cout<<"Scenario #"<<k+<<":"<<endl;
         for(i = ; i < m; ++ i)
         {
             bo = false;
             scanf("%d%d",&u,&v);
             temp1 = u;
             temp2 = v;
             if(i != )
             {
                 temp1 = find_pre(temp1);
                 temp2 = find_pre(temp2);
                 if(temp1 == temp2)
                 {
                     boo = true;
                 //    bo = true;
                 }
             }
             if(!boo)
             {
                 u = find_pre(u);
                 v = find_pre(v);
                 temp1 = comb(u,opp[v]);
                 temp2 = comb(opp[u],v);
                 opp[temp1] = temp2;
                 opp[temp2] = temp1;
             }
         }
         if(boo)
         {
             cout<<"Suspicious bugs found!"<<endl;
         }
         else
         {
             cout<<"No suspicious bugs found!"<<endl;
         }
         cout<<endl;
     }
 }