poj1904 完美匹配+Tarjan

#include<vector>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=4080;
const int M=4e6+88;
vector<int>sc[N];
vector<int>G[N];
int head[N],dfn[N],low[N],q[N];
bool instack[N],mp[2008][2008];
int tot,scnt,l,cnt;
struct node
{
    int to,next;
} e[M];
void add(int u,int v)
{
    e[tot].to=v;
    e[tot].next=head[u];
    head[u]=tot++;
}
void Tarjan(int u)
{
    dfn[u]=low[u]=++cnt;
    q[l++]=u;
    instack[u]=1;
    for(int i=head[u]; ~i; i=e[i].next)
    {
        int v=e[i].to;
        if(!dfn[v])
        {
            Tarjan(v);
            low[u]=min(low[u],low[v]);
        }
        else if(instack[v]&&dfn[v]<low[u]) low[u]=dfn[v];
    }
    if(low[u]==dfn[u])
    {
        ++scnt;
        int t;
        do
        {
            t=q[--l];
            sc[scnt].push_back(t);
            instack[t]=0;
        }
        while(t!=u);
    }
}
int main()
{
    int n,x,y;
    while(scanf("%d",&n)!=EOF)
    {
        tot=scnt=cnt=l=0;
        memset(head,-1,sizeof(head));
        memset(dfn,0,sizeof(dfn));
        memset(mp,0,sizeof(mp));
        for(int i=1; i<=n; ++i)
        {
            scanf("%d",&x);
            while(x--)
            {
                scanf("%d",&y);
                add(i,y+n);
                G[i].clear();
                sc[i].clear();
                mp[i][y]=1;
            }
        }
        for(int i=1; i<=n; ++i)
        {
            scanf("%d",&x);
            add(x+n,i);
        }
        for(int i=1; i<=n; ++i) if(!dfn[i]) Tarjan(i);
        for(int i=1; i<=scnt; ++i) sort(sc[i].begin(),sc[i].end());
        for(int i=1; i<=scnt; ++i)
        {
            int tc=upper_bound(sc[i].begin(),sc[i].end(),n)-sc[i].begin();
            for(int j=0; j<tc; ++j) for(int k=tc; k<(int)sc[i].size(); ++k) if(mp[sc[i][j]][sc[i][k]-n] ) G[sc[i][j]].push_back(sc[i][k]-n);
        }
        for(int i=1; i<=n; ++i)
        {
            printf("%d",(int)G[i].size());
            for(int j=0; j<(int)G[i].size(); ++j) printf(" %d",G[i][j]);
            puts("");
        }
    }
}