「luogu2763」试题库问题

#include<bits/stdc++.h>
using namespace std;
const int N=1050,K=30,oo=1e9;
int k,n,ss,tt,cnt[K];
struct Edge{
    int from,to,flow,cap;
    Edge(int _from=0,int _to=0,int _flow=0,int _cap=0):from(_from),to(_to),flow(_flow),cap(_cap){}
};
vector<int>res[K];
vector<Edge> edge;
int edge_tot;
vector<int>point[N];
void add_edge(int f,int t,int c){
    edge.push_back(Edge(f,t,0,c));
    point[f].push_back(edge_tot++);
    edge.push_back(Edge(t,f,0,0));
    point[t].push_back(edge_tot++);
    return;
}
int level[N];
bool bfs(){
    memset(level,0,sizeof(level));
    queue<int>q;
    q.push(ss);
    level[ss]=1;
    int x;
    while(!q.empty()){
        x=q.front();q.pop();
        for(int i=0;i<point[x].size();i++){
            Edge& e=edge[point[x][i]];
            if(e.cap>e.flow&&!level[e.to]){
                level[e.to]=level[x]+1;
                q.push(e.to);
            }
        }
    }
    return level[tt];
}
int dfs(int k,int aa){
    if(k==tt||!aa) return aa;
    int temp,ans=0;
    for(int i=0;i<point[k].size();i++){
        Edge& e=edge[point[k][i]];
        if(e.cap>e.flow&&level[e.to]==level[k]+1&&(temp=dfs(e.to,min(aa,e.cap-e.flow)))){
            ans+=temp,aa-=temp;
            e.flow+=temp,edge[point[k][i]^1].flow-=temp;
        }
        if(!aa) return ans;
    }
    return ans;
}
int dinic(){
    int ans=0;
    while(bfs()) ans+=dfs(ss,oo);
    return ans;
}
int main(){
    int t1,t2;
    scanf("%d%d",&k,&n);
    ss=k+n+1,tt=ss+1;
    for(int i=1;i<=k;i++){
        scanf("%d",&cnt[i]);
        add_edge(n+i,tt,cnt[i]);
    }
    for(int i=1;i<=n;i++) add_edge(ss,i,1);
    for(int i=1;i<=n;i++){
        scanf("%d",&t1);
        for(int j=1;j<=t1;j++){
            scanf("%d",&t2);
            add_edge(i,t2+n,1);
        }
    }
    dinic();
    for(int i=1;i<=k;i++){
        if(edge[(i-1)<<1].cap>edge[(i-1)<<1].flow){
            printf("No Solution!");
            return 0;
        }
    }
    for(int i=1;i<=n;i++)
        for(int j=0;j<point[i].size();j++){
            if(edge[point[i][j]].flow==1){
                res[edge[point[i][j]].to-n].push_back(i);
                break;
            }
        }
    for(int i=1;i<=k;i++){
        printf("%d:",i);
        for(int j=0;j<res[i].size();j++) printf("%d ",res[i][j]);
        printf("
");
    }
    return 0;
}