Gym - 101981I The 2018 ICPC Asia Nanjing Regional Contest I.Magic Potion 最大流

题面

题意:n个英雄,m个怪兽,第i个英雄可以打第i个集合里的一个怪兽,一个怪兽可以在多个集合里,有k瓶药水,每个英雄最多喝一次,可以多打一只怪兽,求最多打多少只 n,m,k<=500

题解:显然的最大流裸体,多加一个药水点,药酱入度k,然后再连向英雄

        队友抄的模板所以不是我的那个板子

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 struct Edge
  4 {
  5     int from,to,cap,flow;
  6     Edge(int u,int v,int c,int f)
  7     {
  8         from=u;
  9         to=v;
 10         cap=c;
 11         flow=f;
 12     }    
 13 };
 14 const int maxn=2050;
 15 const int INF=0x3f3f3f3f;
 16 struct Dinic
 17 {
 18     int n,m,s,t;
 19     vector<Edge> edges;
 20     vector<int> G[maxn];
 21     int d[maxn];
 22     int cur[maxn];
 23     bool vis[maxn];
 24     void AddEdge(int from,int to, int cap)
 25     {
 26         edges.push_back(Edge(from,to,cap,0));
 27         edges.push_back(Edge(to,from,0,0));
 28         m=edges.size();
 29         G[from].push_back(m-2);
 30         G[to].push_back(m-1);
 31     }
 32     bool BFS()
 33     {
 34         memset(vis,0,sizeof(vis));
 35         queue<int> Q;
 36         Q.push(s);
 37         d[s]=0;
 38         vis[s]=1;
 39         while(!Q.empty())
 40         {
 41             int x=Q.front();
 42             Q.pop();
 43             for(int i=0;i<G[x].size();i++)
 44             {
 45                 Edge& e=edges[G[x][i]];
 46                 if(!vis[e.to]&&e.cap>e.flow)
 47                 {
 48                     vis[e.to]=1;
 49                     d[e.to]=d[x]+1;
 50                     Q.push(e.to);
 51                 }
 52             }
 53         }
 54         return vis[t];
 55     }
 56     int DFS(int x,int a)
 57     {
 58         if(x==t||a==0) return a;
 59         int flow=0,f;
 60         for(int& i=cur[x];i<G[x].size();i++)
 61         {
 62             Edge& e=edges[G[x][i]];
 63             if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0)
 64             {
 65                 e.flow+=f;
 66                 edges[G[x][i]^1].flow-=f;
 67                 flow+=f;
 68                 a-=f;
 69                 if(a==0) break;
 70             }
 71         }
 72         return flow;
 73     }
 74     int Maxflow(int s,int t)
 75     {
 76         this->s=s;this->t=t;
 77         int flow=0;
 78         while(BFS())
 79         {
 80             memset(cur,0,sizeof(cur));
 81             flow+=DFS(s,INF);
 82         }
 83         return flow;
 84     }
 85 }fuck;
 86 int main()
 87 {
 88     int  n,m,k,i,j,tmpn,x;
 89     scanf("%d%d%d",&n,&m,&k);
 90     for(i=1;i<=n;i++)
 91     {
 92         fuck.AddEdge(0,i+1,1);
 93         fuck.AddEdge(1,i+1,1);
 94     }
 95     fuck.AddEdge(0,1,k);
 96     for(i=1;i<=n;i++)
 97     {
 98         scanf("%d",&tmpn);
 99         for(j=1;j<=tmpn;j++)
100         {
101             scanf("%d",&x);
102             fuck.AddEdge(i+1,n+1+x,1);
103         }
104     }
105     for(i=1;i<=m;i++)
106         fuck.AddEdge(n+1+i,n+m+2,1);
107     printf("%d\n",fuck.Maxflow(0,n+m+2));
108     return 0;
109 }