[日常摸鱼]最小费用最大流

模板题：https://www.luogu.org/problemnew/show/P3381

#include<cstdio>
#include<queue>
#include<cstring>
#define rep(i,n) for(register int i=1;i<=n;i++)
#define REP(i,a,b) for(register int i=a;i<=b;i++)
using namespace std;
const int N=5005;
const int M=50005;
const int INF=(~0u>>1);
inline int read()
{
    int s=0,f=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')f=0;c=getchar();}
    while(c>='0'&&c<='9'){s=s*10+c-'0';c=getchar();}
    return f?s:-s;
}
struct edge
{
    int to,nxt,w,c;
    edge(int to=0,int nxt=0,int w=0,int c=0):to(to),nxt(nxt),w(w),c(c){}
}edges[M<<1];
int n,m,s,t,cnt,ans,maxflow;
int head[M<<1],vis[N],d[N],pre[N],infc[N];
queue<int>q;
inline void addEdge(int u,int v,int w,int c)
{
    edges[++cnt]=edge(v,head[u],w,c);head[u]=cnt;
    edges[++cnt]=edge(u,head[v],0,-c);head[v]=cnt;
}
#define cur edges[i].to
inline bool spfa()
{
    memset(vis,0,sizeof vis);rep(i,n)d[i]=INF;
    infc[s]=INF;d[s]=0;q.push(s);vis[s]=1;
    while(!q.empty())
    {
        int k=q.front();q.pop();vis[k]=0;
        for(register int i=head[k];i;i=edges[i].nxt)if(edges[i].w&&d[cur]>d[k]+edges[i].c)
        {
            d[cur]=d[k]+edges[i].c;
            pre[cur]=i;infc[cur]=min(infc[k],edges[i].w);
            if(!vis[cur])
            {
                vis[cur]=1;
                q.push(cur);
            }
        }
    }
    if(d[t]==INF)return 0;
    return 1;
}
#undef cur
inline void updata()
{
    int tmp=t;
    while(tmp!=s)
    {
        int i=pre[tmp];
        edges[i].w-=infc[t];
        edges[i^1].w+=infc[t];
        tmp=edges[i^1].to;
    }
    maxflow+=infc[t];
    ans+=d[t]*infc[t];
}
int main()
{
    cnt=1;n=read();m=read();s=read();t=read();
    rep(i,m)
    {
        int u,v,w,c;u=read();v=read();w=read();c=read(); 
        addEdge(u,v,w,c);
    }
    while(spfa())updata();
    printf("%d %d",maxflow,ans);
    return 0;
}