poj2289 Jamie's Contact Groups（二分答案+最大流）

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 2010
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,h
,num=1,lev
,T=2001,tot=0;
char s[20];
struct edge{
int to,next,val;
}data[1100000];
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));
lev[0]=1;q.push(0);
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=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;
}
inline bool jud(int x){
num=1;int ans=0;
for(int i=1;i<=m;++i) data[++num].val=x,data[++num].val=0;
for(int i=1;i<=n;++i) data[++num].val=1,data[++num].val=0;
while(num<tot) data[++num].val=1,data[++num].val=0;
while(bfs()) ans+=dinic(0,inf);
return ans==n;
}
int main(){
//  freopen("a.in","r",stdin);
while(1){
n=read();m=read();if(!n&&!m) break;
memset(h,0,sizeof(h));num=1;
for(int i=1;i<=m;++i) add(i+n,T,0);
for(int i=1;i<=n;++i) add(0,i,1);
for(int i=1;i<=n;++i){
scanf("%s",s+1);int x=0;
while(1){scanf("%d",&x);add(i,n+x+1,1);char op=getchar();if(op=='\n'||op=='\r') break;}
}int l=n/m,r=n;tot=num;
while(l<=r){
int mid=l+r>>1;
if(jud(mid)) r=mid-1;
else l=mid+1;
}printf("%d\n",r+1);
}return 0;
}