POJ3308[Paratroopers]

最小割,第一次做容量是实数的网络流,WA了N次,一直以为是浮点误差没处理好。


后来才发现是printf(“%lf”,xxx)出了问题,printf有时候不认%lf,但是一定认%f。


CODE:


/*


AUTHOR: Su Jiao


DATE: 2010-7-21


DESCRIPTION:


网络流 乱做


http://acm.pku.edu.cn/JudgeOnline/problem?id=3308


*/


#include <stdio.h>


#include <string.h>


#include <math.h>


 


const double oo=1e10;


const double zero=1e-10;


const int MAXV=1000000;


const int MAXE=1000000;


typedef struct struct_edge* edge;


struct struct_edge{int v;double c;edge n,b;};


struct_edge pool[MAXE];


edge top;


int S,T,V;


edge adj[MAXV];


int d[MAXV];


int q[MAXV];


int head,tail;


void add_edge(int u,int v,double c)


{


     top->v=v,top->c=c,top->n=adj[u],adj[u]=top++;


     top->v=u,top->c=0,top->n=adj[v],adj[v]=top++;


     adj[u]->b=adj[v],adj[v]->b=adj[u];


}


bool is_zero(double a)


{


     return fabs(a)<=zero;


}


bool relabel()


{


     for (int i=0;i<V;d[i++]=V) ;


     d[q[head=tail=0]=T]=0;


     while (head<=tail)


     {


           int u=q[head++];


           for (edge i=adj[u];i;i=i->n)


               if (!is_zero(i->b->c)&&d[i->v]==V)


                  d[q[++tail]=i->v]=d[u]+1;


           if (d[S]!=V) return true;


     }


     return false;


}


double augment(int u,double e)


{


       if (u==T) return e;


       double f=0;


       for (edge i=adj[u];i&&!is_zero(e);i=i->n)


           if (!is_zero(i->c)&&d[u]==d[i->v]+1)


           {


              double df=augment(i->v,e<i->c?e:i->c);


              i->c-=df,i->b->c+=df,e-=df,f+=df;


           }


       return f;


}


double dinic()


{


       double f=0;


       while (relabel()) f+=augment(S,oo);


       return f;


}


 


int t;


int m,n,l;


int main()


{


    scanf(“%d”,&t);


    for (int tt=0;tt<t;tt++)


    {


        scanf(“%d%d%d”,&m,&n,&l);


        top=pool;


        memset(adj,0,sizeof(adj));


        S=0,T=m+n+1,V=m+n+2;


        for (int i=1;i<=m;i++)


        {


            double a;


            scanf(“%lf”,&a);


            add_edge(S,i,log(a));


        }


        for (int i=1;i<=n;i++)


        {


            double a;


            scanf(“%lf”,&a);


            add_edge(i+m,T,log(a));


        }


        for (int i=0;i<l;i++)


        {


            int a,b;


            scanf(“%d%d”,&a,&b);


            add_edge(a,b+m,oo);


        }


        printf(“%.4f\n”,double(exp(dinic())));


    }


}