POJ 3281 Dining

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <vector>
#include <algorithm>
#include <queue>
#include <set>

using namespace std;

const int INF=0x3f3f3f3f;

const int MAXN=2000;

const int MAXM=10005;

int n,u,v;

struct Edge
{
int to,next,flow;
}edge[MAXM];

int head[MAXN],tot;

void add(int u,int v,int w)
{
edge[tot].to=v;
edge[tot].flow=w;
edge[tot].next=head[u];
head[u]=tot++;

edge[tot].to=u;
edge[tot].flow=0;
edge[tot].next=head[v];
head[v]=tot++;
}

int dep[MAXN];

bool bfs(int s,int t)
{
int u;
memset(dep,-1,sizeof(dep));
queue <int> q;
q.push(s);
dep[s]=0;
while(!q.empty())
{
u=q.front();
q.pop();
for(int i=head[u];~i;i=edge[i].next)
{
int v=edge[i].to;
if(dep[v]==-1&&edge[i].flow>0)
{
dep[v]=dep[u]+1;
if(v==t)return true;
q.push(v);
}
}
}
return false;
}

int dfs(int s,int t,int x)
{
if(s==t)return x;int ans=x;
for(int i=head[s];~i;i=edge[i].next)
{
int v=edge[i].to;
if(dep[v]==dep[s]+1&&edge[i].flow>0)
{
int minn=dfs(v,t,min(x,edge[i].flow));
edge[i].flow-=minn;
edge[i^1].flow+=minn;
x-=minn;
}
}
return ans-x;
}

int dinic()
{
int ans=0;
while(bfs(1,n))ans+=dfs(1,n,INF);
return ans;
}

int main()
{
//freopen("in.txt","r",stdin);
int a,b,c,x,y;
while(scanf("%d%d%d",&a,&b,&c)==3)
{
memset(head,-1,sizeof(head));
tot=0;n=2*a+b+c+2;
for(int i=0;i<a;++i)
{
scanf("%d%d",&x,&y);
for(int j=0;j<x;++j)
{
scanf("%d",&u);
//add(1,u+2*a+1,1);
add(u+2*a+1,2+i,1);
}
for(int j=0;j<y;++j)
{
scanf("%d",&v);
//add(2*a+b+1+v,n,1);
add(i+2+a,2*a+b+1+v,1);
}
add(i+2,i+2+a,1);
}
for(int i=0;i<b;++i)add(1,2*a+2+i,1);
for(int i=0;i<c;++i)add(2*a+b+2+i,n,1);
printf("%d\n",dinic());
}
return 0;
}