最小费用最大流模版

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#include <algorithm>
using namespace std;
const int MAXN=5005,MAXM=50005;
int init(){
    int rv=0,fh=1;
    char c=getchar();
    while(c<'0'||c>'9'){
        if(c=='-') fh=-1;
        c=getchar();
    }
    while(c>='0'&&c<='9'){
        rv=(rv<<1)+(rv<<3)+c-'0';
        c=getchar();
    }
    return fh*rv;
}
int n,m,nume,flow,head[MAXN],s,t,pre[MAXN],delta,dis[MAXN];
bool f[MAXN];
queue <int> q;
struct edge{
    int to,nxt,cap,flow,cost;
}e[MAXM<<1];
void adde(int from,int to,int cap,int cost){
    e[++nume].to=to;
    e[nume].cap=cap;
    e[nume].nxt=head[from];
    e[nume].cost=cost;
    head[from]=nume;
}
bool SPFA(){
    memset(dis,0x3f,sizeof(dis));
    memset(pre,0,sizeof(pre));
    q.push(s);f[s]=1;
    dis[s]=0;
    pre[s]=0;
    //for(int i=1;i<=n;i++) cout<<dis[i]<<endl;
    while(!q.empty()){
        int u=q.front();q.pop();
        f[u]=0;
        for(int i=head[u];i;i=e[i].nxt){
            int v=e[i].to;
            if((dis[v]>dis[u]+e[i].cost)&&(e[i].flow<e[i].cap)){
                dis[v]=dis[u]+e[i].cost;
                pre[v]=i;
                if(!f[v]){
                    f[v]=1;
                    q.push(v);
                }
            }
        }
    }
//  cout<<dis[t]<<endl;
    if(dis[t]!=0x3f3f3f3f) return 1;
    else return 0;
}
int mincost;
int main(){
    n=init();m=init();s=init();t=init();
    for(int i=1;i<=m;i++){
        int u=init(),v=init(),cap=init(),cost=init();
        adde(u,v,cap,cost);
        adde(v,u,0,-cost);
    }
    while(SPFA()){
        delta=0x3f3f3f3f;
        for(int i=pre[t];i;i=pre[e[((i-1)^1)+1].to]){
            delta=min(delta,e[i].cap-e[i].flow);
        }
        for(int i=pre[t];i;i=pre[e[((i-1)^1)+1].to]){
            e[i].flow+=delta;
            e[((i-1)^1)+1].flow-=delta;
            mincost+=e[i].cost*delta;
        }
        flow+=delta;
        //cout<<1<<endl;
    }
    printf("%d %d\n",flow,mincost);
    return 0;
}