【费用流】double模板

https://vjudge.net/contest/201468#problem/G
一道费用流，原版来自通酱，被zzb魔改为可用于费用为double
http://www.cnblogs.com/autsky-jadek/p/4149096.html

#include
#include 
#include
#include
#include
using namespace std;
#define MAXN 111
#define MAXM 22001
#define INF 2147483647
int S,T,n,m;
int en,u[MAXM],v[MAXM],first[MAXN],nex[MAXM],cap[MAXM];
double cost[MAXM];//Next Array
bool inq[MAXN];
double d[MAXN]/*spfa*/;
int p[MAXN]/*spfa*/,a[MAXN]/*可改进量*/;
queue<int>q;
void Init_MCMF(){memset(first,-1,sizeof(first));en=0;}

void AddEdge(const int &U,const int &V,const int &W,const double &C)
{
    u[en]=U; v[en]=V; cap[en]=W; cost[en]=C;
    nex[en]=first[U]; first[U]=en++;
    u[en]=V; v[en]=U; cap[en]=0; cost[en]=-C;
    nex[en]=first[V]; first[V]=en++;
}
bool check[ MAXN ];

bool Spfa(int &Flow,double &Cost)
{
    memset(check , 0 ,sizeof( check ) );
    bool op=0;
    memset(inq,0,sizeof(inq));
    d[S]=0; inq[S]=1; p[S]=0; a[S]=INF; q.push(S);
    check[S]=1;
    while(!q.empty())
      {
          int U=q.front(); q.pop(); inq[U]=0;
          for(int i=first[U];i!=-1;i=nex[i])
            if(cap[i] && ( ( check[v[i]]==0)|| (  d[v[i]] > 1e-7+ d[U]+cost[i] ) ) )
              {
                d[v[i]]=d[U]+cost[i];
                check[v[i]]=1;
                p[v[i]]=i;
                a[v[i]]=min(a[U],cap[i]);
                if ( v[i] == T )
                    op=1;
                if(!inq[v[i]]) {q.push(v[i]); inq[v[i]]=1;}
              }
      }
    if ( op==0 )
        return 0;
    //if( fabs( d[T] - 2000000000)<1e-5 )return 0;
    Flow+=a[T]; Cost+=d[T]*a[T]; int U=T;
    while(U!=S)
      {
          cap[p[U]]-=a[T]; cap[p[U]^1]+=a[T];
          U=u[p[U]];
      }
    return 1;
}
double Mincost()
{
    int Flow=0;
    double Cost=0;
    while(Spfa(Flow,Cost));
    //printf("%d\n",Flow);
    return Cost;
}

void doit(){
Init_MCMF();
scanf("%d%d",&n,&m);
S=n+1;T=n+2;
for (int i=1;i<=n;i++)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        AddEdge(S,i,a,0);
        AddEdge(i,T,b,0);
    }
for (int i=1;i<=m;i++)
    {
        int a,b,c;
        double d;
        scanf("%d%d%d%lf",&a,&b,&c,&d);
        if ( c )
        {
            d=-log(1-d);
            //cout<
            if ( c>1)
                AddEdge(a,b,c-1,d);
            AddEdge(a,b,1,0);
        }
    }
printf("%.2f\n",1-exp( -Mincost()  ) );
}

int main(){
    int T;
    scanf("%d",&T);
    for (int i=1;i<=T;i++)
        doit();
    return 0;
}