bzoj2502 清理雪道（有源汇有上下界最小流）

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 110
inline 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,m,s=101,t=102,T=105,h
,num=1,lev
,tot=0,ans=0,in
,cur
;
struct edge{
int to,next,val;
}data[22000];
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];
}
inline int dinic(int x,int low){
if(x==T) return low;int tmp=low;
for(int &i=cur[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;else 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();
for(int i=1;i<=n;++i){
int owo=read();if(!owo) add(i,t,inf);
while(owo--){
int x=read();in[x]++;in[i]--;add(i,x,inf);
}add(s,i,inf);
}for(int i=1;i<=n;++i){
if(in[i]>0) add(0,i,in[i]),tot+=in[i];
if(in[i]<0) add(i,T,-in[i]);
}
while(bfs()){memcpy(cur,h,sizeof(cur));ans+=dinic(0,inf);}
add(t,s,inf);while(bfs()){memcpy(cur,h,sizeof(cur));ans+=dinic(0,inf);}
printf("%d\n",data[num].val);
return 0;
}