hdu 4309 Seikimatsu Occult Tonneru 网络流

来源：互联网发布：sql语句中的关键字编辑：程序博客网时间：2024/06/04 18:58

题意：

有三种不同类型的边，一种可以在里面放人，一种可以任意多人穿过，一种可以过一个人，如果通过了一个人之后可以选择增加花费使得可以通过无限的人数。有N个城市，要把尽可能多的人放在第一种里面，问最少需要多少花费。

思路：

可以转化为网络流模型，第一种边拆开就好，如(x,y)连成，x->u,u->T,x-y，这样就好，其他的就枚举第三种选择那些就好，（因为第三种只有12条）。

代码如下：

#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>#include<queue>#include<set>#include<vector>using namespace std;typedef __int64 ll;const int maxnode=4000+5;const int maxedge=1000000+5;const int oo=1000000000;struct Dinic{    int node,src,dest,nedge;    int head[maxnode],point[maxedge],next[maxedge],flow[maxedge],capa[maxedge];    int dist[maxnode],Q[maxnode],work[maxnode];    void init(int _node,int _src,int _dest)    {        node=_node;        src=_src;        dest=_dest;        for(int i=0; i<node; i++) head[i]=-1;        nedge=0;    }    void addedge(int u,int v,int c1,int c2)    {        point[nedge]=v,capa[nedge]=c1,flow[nedge]=0,next[nedge]=head[u],head[u]=(nedge++);        point[nedge]=u,capa[nedge]=c2,flow[nedge]=0,next[nedge]=head[v],head[v]=(nedge++);    }    bool dinic_bfs()    {        memset(dist,255,sizeof(dist));        dist[src]=0;        int sizeQ=0;        Q[sizeQ++]=src;        for(int cl=0; cl<sizeQ; cl++)        {            for(int k=Q[cl],i=head[k]; i>=0; i=next[i])            {                if(flow[i]<capa[i] && dist[point[i]]<0)                {                    dist[point[i]]=dist[k]+1;                    Q[sizeQ++]=point[i];                }            }        }        return dist[dest]>=0;    }    int dinic_dfs(int x,int exp)    {        if(x==dest) return exp;        for(int &i=work[x]; i>=0; i=next[i])        {            int v=point[i],tmp;            if(flow[i]<capa[i] && dist[v]==dist[x]+1 && (tmp = dinic_dfs(v,min(exp,capa[i]-flow[i])))>0)            {                flow[i]+=tmp;                flow[i^1]-=tmp;                return tmp;            }        }        return 0;    }    int dinic_flow()    {        int result=0;        while(dinic_bfs())        {            for(int i=0; i<node; i++) work[i]=head[i];            while(1)            {                int delta=dinic_dfs(src,oo);                if(delta==0) break;                result +=delta;            }        }        return result;    }} Solver;int N,m;int num_tunnel,num_modern,num_ancient;int num[110];int tun[33],modern[1010],anc[33];int ut[33],vt[33],um[1010],vm[1010],ua[33],va[33];int res,sum_cost;bool choose[33];void cal(){    int tcost=0;    for(int i=1; i<=num_ancient; i++)    {        if(choose[i])tcost+=anc[i];    }//printf("tcost=%d\n",tcost);    if(tcost>=sum_cost)return;    Solver.init(num_tunnel+N+2,0,num_tunnel+N+1);    for(int i=1; i<=N; i++)    {        Solver.addedge(0,i,num[i],0);    }    for(int i=1; i<=num_tunnel; i++)    {        Solver.addedge(N+i,num_tunnel+N+1,tun[i],0);        Solver.addedge(ut[i],N+i,oo,0);        //Solver.addedge(vt[i],N+i,oo,0);        Solver.addedge(ut[i],vt[i],oo,0);    }    for(int i=1; i<=num_modern; i++)    {        Solver.addedge(um[i],vm[i],oo,0);    }    for(int i=1; i<=num_ancient; i++)    {        if(choose[i])        {            Solver.addedge(ua[i],va[i],oo,0);        }        else        {            Solver.addedge(ua[i],va[i],1,0);        }    }    int t=Solver.dinic_flow();    if(t>=res)    {        sum_cost=tcost;    }}void first(){    Solver.init(num_tunnel+N+2,0,num_tunnel+N+1);    for(int i=1; i<=N; i++)    {        Solver.addedge(0,i,num[i],0);    }    for(int i=1; i<=num_tunnel; i++)    {        Solver.addedge(N+i,num_tunnel+N+1,tun[i],0);        Solver.addedge(ut[i],N+i,oo,0);       // Solver.addedge(vt[i],N+i,oo,0);        Solver.addedge(ut[i],vt[i],oo,0);    }    for(int i=1; i<=num_modern; i++)    {        Solver.addedge(um[i],vm[i],oo,0);    }    for(int i=1; i<=num_ancient; i++)    {        Solver.addedge(ua[i],va[i],oo,0);    }    res=Solver.dinic_flow();}void dfs(int ind){    if(ind>num_ancient)    {        //for(int i=1;i<=num_ancient;i++)printf("%d ",choose[i]);printf("\n");        cal();    }    else    {        choose[ind]=false;        dfs(ind+1);        choose[ind]=true;        dfs(ind+1);        choose[ind]=false;    }}int main(){    while(scanf("%d",&N)!=EOF)    {        scanf("%d",&m);        num_tunnel=0;        num_ancient=0;        num_modern=0;        sum_cost=0;        for(int i=1; i<=N; i++)        {            scanf("%d",&num[i]);        }        for(int i=1; i<=m; i++)        {            int u,v,w,p;            scanf("%d%d%d%d",&u,&v,&w,&p);            if(p<0)            {                tun[++num_tunnel]=w;                ut[num_tunnel]=u;                vt[num_tunnel]=v;            }            else if(p==0)            {                modern[++num_modern]=w;                um[num_modern]=u;                vm[num_modern]=v;            }            else            {                sum_cost+=w;                anc[++num_ancient]=w;                ua[num_ancient]=u;                va[num_ancient]=v;            }        }        //printf("@@%d\n",sum_cost);        first();        if(res<=0)        {            printf("Poor Heaven Empire\n");        }        else        {            memset(choose,false,sizeof(choose));            dfs(1);            printf("%d %d\n",res,sum_cost);        }    }    return 0;}

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