bzoj1711 [Usaco2007 Open]Dining吃饭（最大流/三分图匹配）

源点向食物建边，食物向牛建边，牛向饮料建边，饮料向汇点建边，把牛拆成两个，保证一头牛只有1会通过。然后dinic

#include <bits/stdc++.h>using namespace std;#define ll long long#define N 510#define inf 0x3f3f3f3finline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();    return x*f;}int n,f,d,h[N],num=1,lev[N],T=500;struct edge{    int to,next,val;}data[50000];inline void add(int x,int y,int val){    data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=val;    data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=0;}inline bool bfs(){    queue<int>q;memset(lev,0,sizeof(lev));    q.push(0);lev[0]=1;    while(!q.empty()){        int x=q.front();q.pop();        for(int i=h[x];i;i=data[i].next){            int y=data[i].to;if(lev[y]||!data[i].val) continue;            lev[y]=lev[x]+1;q.push(y);        }    }return lev[T];}int dinic(int x,int low){    if(x==T) return low;int tmp=low;    for(int i=h[x];i;i=data[i].next){        int y=data[i].to;if(lev[y]!=lev[x]+1||!data[i].val) continue;        int res=dinic(y,min(tmp,data[i].val));        if(!res) lev[y]=0;tmp-=res;data[i].val-=res;data[i^1].val+=res;        if(!tmp) return low;    }return low-tmp;}int main(){//  freopen("a.in","r",stdin);    n=read();f=read();d=read();    for(int i=1;i<=f;++i) add(0,i+200,1);    for(int i=1;i<=d;++i) add(i+300,T,1);    for(int i=1;i<=n;++i){        int f1=read(),d1=read();add(i,i+100,1);        while(f1--){            int x=read();add(x+200,i,1);        }while(d1--){            int x=read();add(i+100,x+300,1);        }    }int ans=0;while(bfs()) ans+=dinic(0,inf);    printf("%d\n",ans);    return 0;}