luogo_3381模板最小费用最大流

Posted 2020-10-06 Code_Together

#include<bits/stdc++.h>

using namespace std;

#define MAXM 500010

#define MAXN 5010

#define INF 100000000

struct Edge{int from,to,cap,flow,cost;};

int n,m,s,t,allflow,allcost;

vector<Edge> edges;

vector<int> G[MAXN];

int d[MAXN],p[MAXN],a[MAXM];

bool vis[MAXN];

void Addedge(int from,int to,int cap,int cost){

edges.push_back((Edge){from,to,cap,0,cost});

edges.push_back((Edge){to,from,0,0,-cost});

int x=edges.size();

G[from].push_back(x-2);

G[to].push_back(x-1);

}

bool BellmanFord(){

for(int i=1;i<=n;i++)d[i]=INF;

memset(vis,0,sizeof(vis));

d[s]=0; vis[s]=1; p[s]=0; a[s]=INF;

queue<int> Q;

Q.push(s);

while(!Q.empty()){

int u=Q.front(); Q.pop();

vis[u]=0;

for(int i=0;i<G[u].size();i++){

Edge e=edges[G[u][i]];

if(e.cap>e.flow && d[e.to]>d[u]+e.cost){

d[e.to]=d[u]+e.cost;

p[e.to]=G[u][i];

a[e.to]=min(a[u],e.cap-e.flow);

if(!vis[e.to]){Q.push(e.to); vis[e.to]=1;}

}

}

}

if(d[t]==INF)return false;

allflow+=a[t];

allcost+=a[t]*d[t];

int u=t;

while(u!=s){

edges[p[u]].flow+=a[t];

edges[p[u]^1].flow-=a[t];

u=edges[p[u]].from;

}

}

int main(){

scanf("%d%d%d%d",&n,&m,&s,&t);

for(int i=1;i<=m;i++){

int u,v,w,c;

scanf("%d%d%d%d",&u,&v,&w,&c);

Addedge(u,v,w,c);

}

while(BellmanFord());

cout<<allflow<<‘ ‘<<allcost<<endl;

return 0;

}