最小费用最大流模板
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const int INF = 0x3f3f3f3f; typedef long long LL; const int N = 110; struct Edge{ int from, to, cap, flow, cost; Edge(int u,int v,int c,int f,int w):from(u),to(v),cap(c),flow(f),cost(w){} }; struct MCMF{ int n, m; vector<Edge> edges; vector<int> G[N]; int inq[N]; int d[N]; int p[N]; int a[N]; void init(int n){ this->n = n; for(int i = 0; i <= n; i++) G[i].clear(); edges.clear(); } void AddEdge(int from,int to,int cap,long long cost){ edges.push_back(Edge(from,to,cap,0,cost)); edges.push_back(Edge(to,from,0,0,-cost)); m = edges.size(); G[from].push_back(m-2); G[to].push_back(m-1); } bool BellmanFord(int s,int t,int &flow,long long &cost){ for(int i = 0; i <= n; i++) d[i] = INF; memset(inq, 0, sizeof inq); d[s] = 0; inq[s] = 1; p[s] = 0; a[s] = INF; queue<int> Q; Q.push(s); while(!Q.empty()){ int u = Q.front(); Q.pop(); inq[u] = 0; for(int i = 0; i < G[u].size(); i++){ Edge& e = edges[G[u][i]]; if(e.cap>e.flow&&d[e.to]>d[u]+e.cost){ d[e.to] = d[u]+e.cost; p[e.to] = G[u][i]; a[e.to] = min(a[u],e.cap-e.flow); if(!inq[e.to]) {Q.push(e.to); inq[e.to] = 1;} } } } if(d[t]==INF) return false; flow += a[t]; cost += (long long)d[t]*(long long)a[t]; for(int u = t; u!=s; u = edges[p[u]].from){ edges[p[u]].flow+=a[t]; edges[p[u]^1].flow-=a[t]; } return true; } int MincostMaxflow(int s,int t,long long &cost){ int flow = 0; cost = 0; while(BellmanFord(s,t,flow,cost)); return flow; } };
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