P3254 圆桌问题

 

关于网络流解决二分图问题，输出具体方案，看一下残量图的边==0 ？就好

 

#include <iostream>
#include<cmath>
#include <queue>
#include <cstring>
using namespace std;
 const int N =1e4,M=5e5+100;
 const int inf =1e9+7;
 
 int all=1,hd[N],go[M],w[M],nxt[M];
  
 int S,T,n,m;
 int dis[N],ans=0,now[M];
  
 void add_(int x,int y,int z){
     nxt[++all]=hd[x]; hd[x]=all; go[all]=y;
     w[all]=z;
     swap(x,y);
     nxt[++all]=hd[x]; hd[x]=all; go[all]=y;
     w[all]=0;
 }
  bool bfs(){
     for(int i=0;i<N;i++)dis[i]=inf;
     queue<int> q;
     q.push(S);
     now[S]=hd[S];
     dis[S]=0;
      
     while(q.empty()==0){
         int x=q.front();
         q.pop();
         for(int i=hd[x];i;i=nxt[i]){
             int y=go[i];
             if(w[i]>0&&dis[y]==inf){
                 dis[y]=dis[x]+1;
                 now[y]=hd[y];
                 q.push(y);
                 if(y==T) return 1;
             }
         }
     }
     return 0;
 }
 int dfs(int x,int sum){
     if(x==T) return sum;
     int k,res=0;
      
     for(int i=now[x];i&& sum ;i=nxt[i]){
         now[x]=i;
         int y=go[i];
         if(w[i]>0&&(dis[y]==dis[x]+1)){
             k=dfs(y,min(sum,w[i]));
             if(k==0) dis[y]=inf;
             w[i]-=k;
             w[i^1]+=k;
             res+=k;
             sum-=k;
         }
     }
     return res;
 }
  
 signed main(){
 	int i,j,x,Cnt=0;
 	cin>>n>>m; S=0,T=n+m+1;
 	
 	for(i=1;i<=n;i++) 
 		cin>>x,Cnt+=x,add_(S,i,x);
 	for(i=1;i<=n;i++)
 	 for(j=1;j<=m;j++)
 	  add_(i,j+n,1);
 	  
 	for(i=1;i<=m;i++) 
 		cin>>x,add_(i+n,T,x);
 	
 	int ans=0;
 	while(bfs()) ans+=dfs(S,inf);
 	if(ans==Cnt) cout<<1;else cout<<0;cout<<endl;
 	
 	if(ans==Cnt){
 		for(i=1;i<=n;cout<<endl,i++)
 		 for(j=hd[i];j;j=nxt[j]){
 		 	int y=go[j];
 		 	if(y!=S && w[j]==0&&w[j^1]>0) cout<<y-n<< ' ';
 		 }
 	}
 }