最小费用最大流/费用流zkw算法模板（洛谷3381）

#include
#include
#include
#include
#include
#include
#define rep(i,a,b) for(int i=a;i<=b;i++)
#define dep(i,a,b) for(int i=a;i>=b;i--)
#define ll long long
#define inf 1000000000
#define mem(x,num) memset(x,num,sizeof x)
#define reg(x) for(int i=last[x];i;i=e[i].next)
using namespace std;
inline ll read()
{
    ll f=1,x=0;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
const int maxm=1e6+6;
int S,T,ans,n,m,k,cnt=1,que[maxm],d[maxm],last[maxm];
bool inq[maxm];
struct edge{int to,next,v,c;}e[maxm<<2];

void insert(int u,int v,int w,int c){
    e[++cnt]=(edge){v,last[u],w,c};last[u]=cnt;
    e[++cnt]=(edge){u,last[v],0,-c};last[v]=cnt;
}

bool spfa(int S,int T)
{
    mem(inq,0);
    int head=0,tail=1,now;
    rep(i,0,n)d[i]=inf;
    que[0]=T;d[T]=0;inq[T]=1;
    while(headif(e[i^1].v&&d[now]-e[i].cif(!inq[e[i].to])inq[e[i].to]=1,que[tail++]=e[i].to;
        }
        inq[now]=0;
    }
    if(d[S]!=inf)return 1;else return 0;
}

int dfs(int x,int f)
{
    if(x==T)return f;
    int used=0,w;inq[x]=1;
    reg(x)
        if(!inq[e[i].to]&&e[i].v&&d[x]-e[i].c==d[e[i].to]){
            w=dfs(e[i].to,min(e[i].v,f-used));
            if(w)ans+=w*e[i].c,e[i].v-=w,e[i^1].v+=w,used+=w;
            if(used==f)return f;
        }
    return used;
}

void zkw()
{
    int flow=0;
    while(spfa(S,T)){
        inq[T]=1;
        while(inq[T]){mem(inq,0);flow+=dfs(S,inf);}
    }
    cout<' '<int main()
{
    n=read(),m=read(),S=read(),T=read();
    rep(i,1,m){
        int u=read(),v=read(),w=read(),c=read();
        insert(u,v,w,c);
    }
    zkw();
    return 0;
}