【达成】费用流模板

 ZKW费用流，双端队列优化SPFA。

#include<bits/stdc++.h>
#define ll long long
#define maxn 4005
#define inf 1<<30
using namespace std;
int To[maxn],Laxt[maxn],Next[maxn],cap[maxn],cost[maxn],cnt=1;
int N,S,T,ft,fc,st,sc,fee,dis[maxn];
ll ans; //费用 
bool inq[maxn],vis[maxn];
deque<int>q;
void add(int u,int v,int c,int cc){
    Next[++cnt]=Laxt[u];Laxt[u]=cnt;To[cnt]=v;cap[cnt]=c;cost[cnt]=cc;}
bool spfa()
{
    memset(inq,0,sizeof(inq));
    for(int i=0;i<=T;i++) dis[i]=inf;
    inq[T]=1; dis[T]=0; q.push_back(T);
    while(!q.empty())
    {
        int u=q.front(); q.pop_front();
        inq[u]=0;
        for(int i=Laxt[u];i;i=Next[i])
        {
            int v=To[i];
            if(cap[i^1]&&dis[v]>dis[u]-cost[i])
            {
                dis[v]=dis[u]-cost[i];
                if(!inq[u]){
                    inq[v]=1;
                    if(q.empty()||dis[v]>dis[q.front()]) q.push_back(v);
                    else q.push_front(v);
                }
            }
        }
    }
    return dis[S]<inf;
}
int dfs(int u,int flow)
{
    vis[u]=1;
    if(u==T||flow==0) return flow;
    int tmp,delta=0;
    for(int i=Laxt[u];i;i=Next[i])
    {
        int v=To[i];
        if((!vis[v])&&cap[i]&&dis[v]==dis[u]-cost[i])
        {
            tmp=dfs(v,min(cap[i],flow-delta));
            delta+=tmp; cap[i]-=tmp; cap[i^1]+=tmp;
        }
    }
    return delta;
}
int main()
{
    
    printf("%lld",ans);
    return 0;
}

 【参考】：https://www.cnblogs.com/rir1715/p/8024648.html