网络最大流
#include<cstdio> #include<cstring> #include<string> #include<cmath> #include<vector> #include<queue> #include<algorithm> using namespace std; const int maxn=2000+10; const int INF=0x7FFFFFFF; struct Edge { int from,to,cap,flow; }; vector<Edge>edges; vector<int>G[maxn]; bool vis[maxn]; int d[maxn]; int cur[maxn]; int numc[maxn]; int numr[maxn]; int K[maxn][105]; int n,m,s,t; int N,M,A,LS; //求出层次网络 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]; } //加边 void AddEdge(int from,int to,int cap) { Edge r; r.from=from; r.to=to; r.cap=cap; r.flow=0; edges.push_back(r); Edge d; d.from=to; d.to=from; d.cap=0; d.flow=0; edges.push_back(d); m=edges.size(); G[from].push_back(m-2); G[to].push_back(m-1); } //每个阶段来一次DFS增广 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==0) break; } } return flow; } //多个阶段,多次建立层次网络。 int Maxflow(int ss,int tt) { int flow=0; while(BFS()) { memset(cur,0,sizeof(cur)); flow+=DFS(ss,INF); } return flow; } int main() { int i,j; while(~scanf("%d%d",&M,&N)) { memset(K,0,sizeof(K)); edges.clear(); for(int i=0; i<maxn; i++) G[i].clear(); for(i=1; i<=M; i++) scanf("%d",&numc[i]); s=1,t=2+N; for(i=2; i<=N+1; i++) { scanf("%d",&A); for(j=1; j<=A; j++) { scanf("%d",&LS); K[LS][0]++; K[LS][K[LS][0]]=i; } scanf("%d",&numr[i]); } for(i=2; i<=N+1; i++) AddEdge(i,t,numr[i]); for(i=1; i<=M; i++) { for(j=1; j<=K[i][0]; j++) { if(j==1) AddEdge(1,K[i][j],numc[i]); else AddEdge(K[i][j-1],K[i][j],INF); } } printf("%d\n",Maxflow(s,t)); } return 0; }
时间: 2024-10-07 21:35:59