【模板】 最小费用最大流

#include<queue>
#include<cstdio>
#include<cstring>
#include<iostream>
#define MAXN 500010

using namespace std;

int n,m,s,t,ans1,ans2;

int pre[MAXN],fee[MAXN];

struct node {
    int to;
    int next;
    int val;
    int cost;
};
node e[MAXN];

int head[MAXN],tot=1;

bool vis[MAXN];

const int INF=0x7fffffff;

queue<int> q;

inline void read(int&x) {
    int f=1;x=0;char c=getchar();
    while(c>'9'||c<'0') {if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9') {x=(x<<1)+(x<<3)+c-48;c=getchar();}
    x=x*f;
}

inline void add(int x,int y,int val,int cost) {
    e[++tot].to=y;
    e[tot].cost=cost;
    e[tot].val=val;
    e[tot].next=head[x];
    head[x]=tot;
}

inline void add_edge(int x,int y,int val,int cost) {
    add(x,y,val,cost);
    add(y,x,0,-cost);
}

inline int max_flow() {
    int flow=INF;
    for(int i=pre[t];i;i=pre[e[i^1].to])
      flow=min(flow,e[i].val);
    for(int i=pre[t];i;i=pre[e[i^1].to]) 
      e[i].val-=flow,e[i^1].val+=flow;
    return flow;
}

inline bool spfa() {
    for(int i=1;i<=n;i++) vis[i]=false,pre[i]=-1,fee[i]=INF;
    while(!q.empty()) q.pop();
    fee[s]=0;
    vis[s]=true;
    pre[s]=0;
    q.push(s);
    while(!q.empty()) {
        int u=q.front();
        q.pop();
        vis[u]=false;
        for(int i=head[u];i!=-1;i=e[i].next) {
            int to=e[i].to;
            if(fee[u]+e[i].cost<fee[to]&&e[i].val) {
                fee[to]=fee[u]+e[i].cost;
                pre[to]=i;
                if(!vis[to]) {
                    q.push(to);
                    vis[to]=true;
                }
            }
        }
    }
    return fee[t]!=INF;
}

int main() {
    int x,y,val,cost;
    read(n);read(m);read(s);read(t);
    memset(head,-1,sizeof head);
    for(int i=1;i<=m;i++) {
        read(x);read(y);read(val);read(cost);
        add_edge(x,y,val,cost);
    }
    while(spfa()) {
        int tt=max_flow();
        ans1+=tt;
          ans2+=tt*fee[t];
    }
    printf("%d %d
",ans1,ans2);
    return 0;
}