最小费用流算法模板

//最小费用流 //memset(head,-1,(n+2)*sizeof(int)); //en=0; struct edge{ int x,y,f,c,nxt; }e[E]; int en,head[N],pre[N],dist[N],visited[N]; void add(int x,int y,int f,int c){ e[en].x=x; e[en].y=y; e[en].f=f; e[en].c=c; e[en].nxt=head[x]; head[x]=en++; } void addedge(int x,int y,int f,int c){ add(x,y,f,c); add(y,x,0,-c); } bool spfa(int s,int t,int n){ int i,v,cur; queue<int> q; for(i=0;i<n;i++){ pre[i]=-1; visited[i]=false; dist[i]=inf; } visited[s]=true; dist[s]=0; q.push(s); while(!q.empty()){ cur=q.front(); q.pop(); visited[cur]=false; for(i=head[cur];i!=-1;i=e[i].nxt) if(e[i].f){ v=e[i].y; if(dist[v]>dist[cur]+e[i].c){ dist[v]=dist[cur]+e[i].c; pre[v]=i; if(!visited[v]){ visited[v]=true; q.push(v); } } } } return dist[t]!=inf; } int cost(int s,int t,int n){ int i,flow=inf,ans=0; while(spfa(s,t,n)){ ans+=dist[t]; for(i=pre[t];i!=-1;i=pre[e[i].x]) flow=min(flow,e[i].f); for(i=pre[t];i!=-1;i=pre[e[i].x]){ e[i].f-=flow; e[i^1].f+=flow; } } return ans; }