[洛谷P3381]【模板】最小费用最大流

%:pragma GCC optimize("Ofast") 
#include<cstdio>
#include<cctype>
#include<cstring>
#define INF 0x3f3f3f3f
#define min(a,b) (((a)<(b))?(a):(b))
char buf[3000020];
int bufpos,n,m,head[5005],cnt,dis[5005],pre_e[5005],a[5005];
bool vis[5005];
int q[30002];
struct edges{
	int from,to,cap,cost,nxt;
}e[110005];
inline void init(){
	bufpos=0;
	buf[fread(buf,1,3000000,stdin)]=‘\0‘;
}
inline int readint(){
	int p=0;
	for(;!isdigit(buf[bufpos]);bufpos++);
	for(;isdigit(buf[bufpos]);bufpos++)
	p=(p<<3)+(p<<1)+buf[bufpos]-‘0‘;
	return p;
}
inline void addedge(int from,int to,int cap,int cost){
	e[++cnt].from=from;
	e[cnt].to=to;
	e[cnt].cap=cap;
	e[cnt].cost=cost;
	e[cnt].nxt=head[from];
	head[from]=cnt;
	e[++cnt].from=to;
	e[cnt].to=from;
	e[cnt].cap=0;
	e[cnt].cost=-cost;
	e[cnt].nxt=head[to];
	head[to]=cnt;
}
bool spfa(int s,int t,int& flow,int& cost){
	memset(dis,0x3f,sizeof dis);
	memset(pre_e,0,sizeof pre_e);
	memset(a,0x3f,sizeof a);
	memset(vis,0,sizeof vis);
	dis[s]=0;
	vis[s]=1;
	q[1]=s;
	int l=0,r=1;
	while(l!=r){
		int u=q[l=l%30000+1];
		vis[u]=0;
		for(int i=head[u];i;i=e[i].nxt){
			if(e[i].cap&&dis[e[i].to]>dis[u]+e[i].cost){
				dis[e[i].to]=dis[u]+e[i].cost;
				pre_e[e[i].to]=i;
				a[e[i].to]=min(a[u],e[i].cap);
				if(!vis[e[i].to]){
					vis[e[i].to]=1;
					q[r=r%30000+1]=e[i].to;
				}
			}
		}
	}
	if(dis[t]==INF)return 0;
	flow+=a[t];
	cost+=dis[t]*a[t];
	for(int i=t;i!=s;i=e[pre_e[i]].from){
		e[pre_e[i]].cap-=a[t];
		e[pre_e[i]^1].cap+=a[t];
	}
	return 1;
}
int main(){
	#ifdef DEBUG
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
	#endif
	init();
	cnt=1;
	n=readint(),m=readint();
	int s=readint(),t=readint();
	for(;m--;){
		int u=readint(),v=readint(),w=readint(),f=readint();
		addedge(u,v,w,f);
	}
	int flow=0,cost=0;
	while(spfa(s,t,flow,cost));
	printf("%d %d\n",flow,cost);
	return 0;
}