bzoj 1823: [JSOI2010]满汉全席

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 using namespace std;
 int t,n,m,head[],next[],v[],cnt,dfn[],cnt1,low[];
 int zhan[],zhan1[],top,shu[],shu1;
 int du()
 {
     int a1;
     char ch;
     ch=getchar();
     for(;ch!='m'&&ch!='h';ch=getchar());
     scanf("%d",&a1);
     if(ch=='m')
       return a1*;
     else
       return a1*-;
 }
 void jia(int a1,int a2)
 {
     cnt++;
     next[cnt]=head[a1];
     head[a1]=cnt;
     v[cnt]=a2;
     return;
 }
 void dfs(int a1)
 {
     cnt1++;
     low[a1]=dfn[a1]=cnt1;
     zhan[a1]=;
     top++;
     zhan1[top]=a1;
     for(int i=head[a1];i;i=next[i])
       if(!dfn[v[i]])
         {
             dfs(v[i]);
             low[a1]=min(low[a1],low[v[i]]);
         }
       else
         if(zhan[v[i]])
           low[a1]=min(low[a1],dfn[v[i]]);
     if(low[a1]==dfn[a1])
       {
         shu1++;
         for(int i=zhan1[top];i!=a1;top--,i=zhan1[top])
           {
             shu[i]=shu1;
             zhan[i]=;
             }
         top--;
         shu[a1]=shu1;
         zhan[a1]=;
       }
     return;
 }
 int main()
 {
     scanf("%d",&t);
     for(int i=;i<t;i++)
       {
         memset(next,,sizeof(next));
         shu1=;
         top=;
         cnt=;
         cnt1=;
         scanf("%d %d",&n,&m);
         for(int i=;i<=*n;i++)
           head[i]=dfn[i]=;
         for(int j=;j<m;j++)
           {
             int a1,a2,b1,b2;
             a1=du();
             b1=du();
             if(a1%==)
               a2=a1-;
             else
               a2=a1+;
             if(b1%==)
               b2=b1-;
             else
               b2=b1+;
             jia(a2,b1);
             jia(b2,a1);
             }

     for(int i=;i<=*n;i++)
       if(dfn[i]==)
         dfs(i);
     int kg=;
     for(int i=;i<=n;i++)
       if(shu[i*]==shu[i*-])
         {
             kg=;
             printf("BAD\n");
             break;
         }
     if(kg)
       printf("GOOD\n");
     }
   return ;
 }

2-set问题，根据评委需求建边，比如h1，h2那m2向h1建边，m1向h2建边。求2-set时用tarjin找环。