【网络流24题-7】洛谷P2763 试题库问题

https://www.luogu.org/problemnew/show/P2763

#include <bits/stdc++.h>
using namespace std;
const int maxn=1115;
const int INF=0x3f3f3f3f;

struct Edge{
	int from,to,cap,flow;
};

struct Dinic{
	int n1,n2,m,s,t;
	vector<Edge> edges;
	vector<int> G[maxn];
	bool vis[maxn];
	int d[maxn];
	int cur[maxn];

	void init()
	{
		int x,y;
		cin>>n1>>n2;
		s=0;t=n1+n2+1;
		for(int i=1;i<=n1;i++)
		{
			scanf("%d",&x);
			AddEdge(s,i,x);
		}
		for(int i=n1+1;i<=n1+n2;i++)
		{
			cin>>x;
			while(x--)
			{
				cin>>y;
				AddEdge(y,i,1);
			}
			AddEdge(i,t,1);
		}
	}

	void AddEdge(int f,int t,int c)
	{
		edges.push_back((Edge){f,t,c,0});
		edges.push_back((Edge){t,f,0,0});
		m=edges.size();
		G[f].push_back(m-2);
		G[t].push_back(m-1);
	}

	bool bfs()
	{	
		memset(vis,0,sizeof(vis));
		queue<int> Q;
		Q.push(s);
		d[s]=0;
		vis[s]=1;
		while(!Q.empty())
		{
			int x=Q.front();Q.pop();
			for(int i=0;i<G[x].size();i++)
			{
				Edge& e=edges[G[x][i]];
				if(!vis[e.to] && e.cap>e.flow)
				{
					vis[e.to]=1;
					d[e.to]=d[x]+1;
					Q.push(e.to);
				}
			}
		}
		return vis[t];
	}

	int dfs(int x,int a)
	{
		if(x==t || a==0)return a;
		int flow=0,f;
		for(int& i=cur[x];i<G[x].size();i++)
		{
			Edge& e=edges[G[x][i]];
			if(d[x]+1==d[e.to] && (f=dfs(e.to,min(a,e.cap-e.flow)))>0)
			{
				e.flow+=f;
				edges[G[x][i]^1].flow-=f;
				flow+=f;
				a-=f;
				if(!a)break;
			}
		}
		return flow;
	}

	int MaxFlow()
	{
		int flow=0;
		while(bfs())
		{
			memset(cur,0,sizeof(cur));
			flow+=dfs(s,INF);
		}	
		return flow;
	}

	void print()
	{
		for(int i=1;i<=n1;i++)
		{
			printf("%d:",i);
			for(int j=0;j<G[i].size();j++)
			{
				int to=edges[G[i][j]].to,flow=edges[G[i][j]].flow;
				if(to!=s&&flow)
				{
					printf(" %d",to-n1);
				}
			}
			putchar('\n');
		}
	}	
}ans;

int main()
{
	//freopen("input.in","r",stdin);
	ans.init();
	ans.MaxFlow();
	ans.print();
	return 0;
}