Spfa费用流模板

 const int INF=;
 const int maxn=,maxm=;
 int cnt=,fir[maxn],nxt[maxm],to[maxm];
 int cap[maxm],val[maxm],dis[maxn],path[maxn];

 void add(int a,int b,int c,int v){
     nxt[++cnt]=fir[a];to[cnt]=b;
     cap[cnt]=c;val[cnt]=v;fir[a]=cnt;
 }
 void addedge(int a,int b,int c,int v){
     add(a,b,c,v);
     add(b,a,,-v);
 }

 int S,T;
 int vis[maxn];
 int Spfa(){
     deque<int>q;
     memset(dis,,sizeof(dis));
     memset(vis,,sizeof(vis));
     q.push_front(S);
     dis[S]=;vis[S]=;
     while(!q.empty()){
         int x=q.front();q.pop_front();vis[x]=;
         for(int i=fir[x];i;i=nxt[i])
             if(cap[i]&&dis[x]+val[i]<dis[to[i]]){
                 dis[to[i]]=val[i]+dis[x];
                 path[to[i]]=i;
                 if(vis[to[i]])continue;
                 if(dis[to[i]]<dis[x])
                     q.push_front(to[i]);
                 else
                     q.push_back(to[i]);
                 vis[to[i]]=;
             }
     }
     return dis[T]==dis[T+]?:dis[T];
 }

 int Aug(){
     int p=T,f=INF;
     while(p!=S){
         f=min(f,cap[path[p]]);
         p=to[path[p]^];
     }
     p=T;
     while(p!=S){
         cap[path[p]]-=f;
         cap[path[p]^]+=f;
         p=to[path[p]^];
     }
     return f;
 }

 int MCMF(){
     int ret=,d;
     while(d=Spfa())
         ret+=Aug()*d;
     return ret;
 }

 #include <queue>
 using namespace std;
 const int maxn=;
 const int maxm=;
 const int INF=;
 int n,m,w[maxn],cnt,fir[maxn],to[maxm],nxt[maxm];
 int cap[maxm],val[maxm],path[maxn],vis[maxn],dis[maxn];
 queue<int>q;
 struct Net_Flow{
     Net_Flow(){cnt=;}

     void add(int a,int b,int c,int v){
         nxt[++cnt]=fir[a];cap[cnt]=c;
         to[cnt]=b;val[cnt]=v;fir[a]=cnt;
     }

     void addedge(int a,int b,int c,int v){
         add(a,b,c,v);add(b,a,,-v);
     }

     int Spfa(int S,int T){
         memset(dis,,sizeof(dis));
         q.push(S);vis[S]=;dis[S]=;
         while(!q.empty()){
             int x=q.front();q.pop();vis[x]=;
             for(int i=fir[x];i;i=nxt[i])
                 if(cap[i]&&dis[to[i]]>dis[x]+val[i]){
                     dis[to[i]]=dis[x]+val[i];
                     if(!vis[to[i]])q.push(to[i]);
                     vis[to[i]]=;path[to[i]]=i;
                 }
         }
         return dis[T];
     }

     int Aug(int S,int T){
         int p=T,f=INF;
         while(p!=S){
             f=min(f,cap[path[p]]);
             p=to[path[p]^];
         }p=T;
         while(p!=S){
             cap[path[p]]-=f;
             cap[path[p]^]+=f;
             p=to[path[p]^];
         }
         return f;
     }

     int MCMF(int S,int T){
         int v=,d;
         while((d=Spfa(S,T))!=INF)
             v+=d*Aug(S,T);
         return v;
     }
 }mcmf;