• [模板]费用流dijistra版


    #pragma GCC optimize(2)
    #include<bits/stdc++.h>
    //#define int long long
    using namespace std;
    const int inf=0x3f3f3f3f;
    const int N=5010,M=2e5+10;
    int n,m,s,t,h[N],d[N],v[N],e[N],res,maxflow;
    int head[N],nex[M],to[M],w[M],flow[M],tot=1;
    inline void ade(int a,int b,int c,int d){
        to[++tot]=b; nex[tot]=head[a]; w[tot]=d; flow[tot]=c; head[a]=tot;
    }
    inline void add(int a,int b,int c,int d){ade(a,b,c,d);    ade(b,a,0,-d);}
    inline int dijkstra(){
        memset(d,0x3f,sizeof d);    d[s]=0;    int vis[N]={0};
        priority_queue<pair<int,int> > q;    q.push({0,s});
        while(q.size()){
            int u=q.top().second;    q.pop();
            if(vis[u])    continue;    vis[u]=1;
            for(int i=head[u];i;i=nex[i]){
                if(flow[i]&&d[to[i]]>d[u]+w[i]+h[u]-h[to[i]]){
                    d[to[i]]=d[u]+w[i]+h[u]-h[to[i]];
                    v[to[i]]=u; e[to[i]]=i;    q.push({-d[to[i]],to[i]});
                }
            }
        }
        for(int i=1;i<=n;i++)    if(d[i]<inf)    h[i]+=d[i];
        return d[t]<inf;
    }
    void EK(){
        while(dijkstra()){
            int mi=inf;
            for(int i=t;i!=s;i=v[i])    mi=min(mi,flow[e[i]]);
            for(int i=t;i!=s;i=v[i])    flow[e[i]]-=mi,flow[e[i]^1]+=mi;
            res+=h[t]*mi,maxflow+=mi;
        }
    }
    signed main(){
        cin>>n>>m>>s>>t;
        for(int i=1,a,b,c,d;i<=m;i++)    scanf("%d %d %d %d",&a,&b,&c,&d),add(a,b,c,d);
        EK();    cout<<maxflow<<' '<<res<<endl;
        return 0;
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/Ketchum/p/13322874.html
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