luoguP1361 小M的作物 最小割
非常经典的最小割模型.
code:
#include <bits/stdc++.h> #define N 3006 #define ll long long #define setIO(s) freopen(s".in","r",stdin) using namespace std; const ll inf=2000000001; namespace net { struct Edge { int u,v; ll c; Edge(int u=0,int v=0,ll c=0):u(u),v(v),c(c){} }; queue<int>q; vector<Edge>edges; vector<int>G[N]; int vv[N],vis[N],d[N],s,t; void add(int u,int v,ll c) { edges.push_back(Edge(u,v,c)); edges.push_back(Edge(v,u,0)); int o=edges.size(); G[u].push_back(o-2); G[v].push_back(o-1); } ll dfs(int x,ll cur) { if(x==t) return cur; ll an=0,flow=0; for(int i=vv[x];i<G[x].size();++i,++vv[x]) { Edge e=edges[G[x][i]]; if(e.c>0&&d[e.v]==d[x]+1) { an=dfs(e.v,min(cur,e.c)); if(an) { cur-=an; flow+=an; edges[G[x][i]].c-=an; edges[G[x][i]^1].c+=an; if(!cur) break; } } } return flow; } int bfs() { memset(vis,0,sizeof(vis)); d[s]=0; vis[s]=1; q.push(s); while(!q.empty()) { int u=q.front(); q.pop(); for(int i=0;i<G[u].size();++i) { if(edges[G[u][i]].c>0) { int v=edges[G[u][i]].v; if(!vis[v]) { vis[v]=1; d[v]=d[u]+1; q.push(v); } } } } return vis[t]; } ll maxflow() { ll re=0; while(bfs()) { memset(vv,0,sizeof(vv)); re+=(ll)dfs(s,inf); } return re; } }; ll a[N],b[N]; int main() { // setIO("input"); int n; scanf("%d",&n); for(int i=1;i<=n;++i) scanf("%lld",&a[i]); for(int i=1;i<=n;++i) scanf("%lld",&b[i]); int s=0,t=n+1,m,tot=n+2; scanf("%d",&m); ll Sum=0; for(int i=1;i<=m;++i) { int k; ll c1,c2; scanf("%d%lld%lld",&k,&c1,&c2); Sum+=c1+c2; int n1=++tot,n2=++tot; net::add(s,n1,c1); net::add(n2,t,c2); for(int j=1;j<=k;++j) { int x; scanf("%d",&x); net::add(n1,x,inf); net::add(x,n2,inf); } } for(int i=1;i<=n;++i) { net::add(s,i,a[i]); net::add(i,t,b[i]); Sum+=a[i]+b[i]; } net::s=s,net::t=t; printf("%lld\n",Sum-net::maxflow()); return 0; }