最小费用最大流模版(zkw)洛谷3381

zkw费用流模版

洛谷上可以测.
其实就是把dinic里的bfs换成了spfa,建图的时候把反向边的容量设为0，费用设为-c[i].
然后跑一边模版。。

#include
#include
#include
#include
using namespace std;
#define maxn 1000010
const int inf=1e9+7;
inline int read(){
    int ret=0,ff=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){
        if(ch=='-') ff=-ff;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9'){
        ret=ret*10+ch-'0';
        ch=getchar();
    }
    return ret*ff;
}
struct Edge{
    int u,v,w,c,next;
}E[maxn];
int n,m,s,t;
int ecnt=1,head[maxn];
void addedge(int u,int v,int w,int c){
    E[++ecnt].u=u;
    E[ecnt].v=v;
    E[ecnt].w=w;
    E[ecnt].c=c;
    E[ecnt].next=head[u];
    head[u]=ecnt;
}
void Addedge(int u,int v,int w,int c){
    addedge(u,v,w,c);
    addedge(v,u,0,-c);
}
int bns=0;
int dis[maxn];
bool vis[maxn];
bool spfa(){
    queue<int> q;
    q.push(t);
    for(int i=1;i<=n;++i) dis[i]=inf;
    vis[t]=1;
    dis[t]=0;
    while(!q.empty()){
        int x=q.front();
        q.pop();
        vis[x]=0;
        for(int i=head[x];i;i=E[i].next){
            int v=E[i].v;
            if(!E[i^1].w||dis[x]+E[i^1].c>=dis[v]) continue;
            dis[v]=dis[x]+E[i^1].c;
            if(!vis[v]){
                vis[v]=1;
                q.push(v);
            }
        }
    }
    return dis[s]!=inf;
}
int dfs(int x,int nar){
    vis[x]=1;
    if(x==t) return nar;
    int used=0;
    for(int i=head[x];i;i=E[i].next){
        int v=E[i].v;
        if(!E[i].w||dis[x]-E[i].c!=dis[v]||vis[v]) continue;
        int tmp=nar-used;
        int flow=dfs(v,min(tmp,E[i].w));
        used+=flow;
        bns+=flow*E[i].c;
        E[i].w-=flow;
        E[i^1].w+=flow;
        if(used==nar) return nar;
    }
    if(!used) dis[x]=-1;
    return used;
}
void zkw(){
    int ans=0;
    while(spfa()){
        vis[t]=1;
        while(vis[t]){
            memset(vis,0,sizeof(vis));
            ans+=dfs(s,inf);
        }
        memset(vis,0,sizeof(vis));
    }
    printf("%d %d\n",ans,bns);
}
int main(){
    //freopen("luogu3881.in","r",stdin);
    n=read(),m=read(),s=read(),t=read();
    for(int i=1;i<=m;++i){
        int a=read(),b=read(),c=read(),d=read();
        Addedge(a,b,c,d);
    }
    zkw();
    return 0;
}