POJ 2289 Jamie's Contact Groups 二分图多重匹配

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
const ll mod=1e9+7;
const ll inf=1e18;
const int N=2e3+20;
int n,m,linker[N][N],vis[N],cap,num[N];
int g[N][N];
bool dfs(int u)
{
	for(int i=1;i<=m;i++)
	{
		if(g[u][i]&&vis[i]==0)
		{
			vis[i]=1;
			if(num[i]<cap) 
			{
				linker[i][++num[i]]=u;	
				return true;
			}
			for(int v=1;v<=num[i];v++)
			{
				if(dfs(linker[i][v]))
				{
					linker[i][v]=u;
					return true;
				}
			}
		
		}
	}
	return false;
}
bool check(int mid)
{
	cap=mid;
	int res=0;
	memset(num,0,sizeof(num));
	for(int i=1;i<=n;i++)
	{
		memset(vis,0,sizeof(vis));
		if(dfs(i))
			res++;
	}
	return res==n;
	
}
int main()
{
	while(cin>>n>>m&&(n+m))
	{
		memset(g,0,sizeof(g));
		char c,s[20];
		for(int i=1;i<=n;i++)
		{
			scanf("%s",s);
			int x;
			while(true)
			{
				scanf("%d%c",&x,&c);
				x++;
				g[i][x]=1;
				if(c==‘\n‘)
					break;
			}
		}
		int ans=0,l=0,r=n;
		while(l<=r)
		{
			int mid=(l+r)>>1;
			if(check(mid))
				ans=mid,r=mid-1;
			else
				l=mid+1;
		}
		cout<<ans<<endl;
	}
	return 0;
}