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P2763 试题库问题

假设一个试题库中有

任务：

求满足要求的组卷方案。

试卷和类别连线(z=1) ,S和题目连线(z=1) 类别和T连线( z=m[i] )

100

101

102

103

104

105

106

#include <iostream>
#include<queue>
#include <cstring>
#define IOS std::ios::sync_with_stdio(0)
using namespace std;
 const int N =1000,M=5e5+100;
 
 const int inf =0x3f3f3f3f;
 int R[N],a[N];
 int all=1,hd[N],go[M],w[M],nxt[M];
   
 int S,T,n,m;
 int dis[M],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(){
     memset(dis,0x3f,sizeof dis);
     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&∑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;
 }
  
  
 void print(int x){
    for(int i=hd[x];i;i=nxt[i]){
        int y=go[i];
        if(y<=n && w[i]) cout<<y<<' ' ;
    }
 }
 signed main(){
    int K;
    cin>>K>>n;
     S=0; T=n+K+1; 
     
    for(int i=1,c;i<=K;++i){
        cin>>c;
        m+=c;
        add_(i+n,T,c);
    }
    for(int i=1;i<=n;i++){
        add_(S,i,1) ;
    }
    for(int i=1,x;i<=n;++i){
        int tes; 
        cin>>tes;
        while(tes--){
            cin>>x;
            add_(i,x+n,1);
        }
    }
     
    int ans=0;
    while(bfs()) ans+=dfs(S,inf);
     
    if(ans==m){
        for(int i=1;i<=K;++i){
            printf("%d: ",i); 
            print(n+i);
            cout<<'\n';
        }
    }
    else{
        printf("No Solution!\n");
    }
    return 0;
}