bzoj2285

完全是为了拼凑才出出来的吧
先分数规划求出到基地入口的最小安全系数
然后再最小点权覆盖集，只不过这里是带一定精度实数的流，其实是一样的

 const inf=;
       eps=0.001;
 type way=record
        po,next,ti,sa:longint;
      end;
      node=record
        po,next:longint;
        flow:double;
      end;

 var w:array[..] of way;
     e:array[..] of node;
     d:array[..] of double;
     numh,h,pp,p,cur,pre:array[..] of longint;
     q:array[..] of longint;
     v:array[..] of boolean;
     i,t,n,m,m1,len,x,y,z,b:longint;
     ans:double;

 function min(a,b:double):double;
   begin
     if a>b then exit(b) else exit(a);
   end;

 procedure add(x,y,a,b:longint);
   begin
     inc(len);
     w[len].po:=y;
     w[len].ti:=a;
     w[len].sa:=b;
     w[len].next:=pp[x];
     pp[x]:=len;
   end;

 procedure ins(x,y:longint;f:double);
   begin
     inc(len);
     e[len].po:=y;
     e[len].flow:=f;
     e[len].next:=p[x];
     p[x]:=len;
   end;

 function check(t:longint;m:double):boolean;
   var x,y,f,r,i:longint;
   begin
     for i:= to n do
       d[i]:=inf;
     d[n]:=;
     fillchar(v,sizeof(v),false);
     f:=;
     r:=;
     q[]:=n;
     while f<=r do
     begin
       x:=q[f];
       v[x]:=false;
       i:=pp[x];
       while i<> do
       begin
         y:=w[i].po;
         if d[y]>d[x]+w[i].ti-m*w[i].sa then
         begin
           d[y]:=d[x]+w[i].ti-m*w[i].sa;
           if (y=t) and (d[y]<=) then exit(true);
           if not v[y] then
           begin
             v[y]:=true;
             inc(r);
             q[r]:=y;
           end;
         end;
         i:=w[i].next;
       end;
       inc(f);
     end;
     if d[t]<= then exit(true) else exit(false);
   end;

 function calc(x:longint):double;
   var l,r,m:double;
   begin
     l:=;
     r:=;
     if not check(x,) then exit(inf);
     while r-l>eps do
     begin
       m:=(l+r)/;
       if check(x,m) then r:=m else l:=m;
     end;
     exit(r);
   end;

 procedure sap;
   var u,i,j,tmp,q:longint;
       neck:double;
   begin
     u:=;
     for i:= to t do
       cur[i]:=p[i];
     numh[]:=t+;
     neck:=inf;
     while h[]<t+ do
     begin
       d[u]:=neck;
       i:=cur[u];
       while i<>- do
       begin
         j:=e[i].po;
         if (e[i].flow>) and (h[u]=h[j]+) then
         begin
           pre[j]:=u;
           cur[u]:=i;
           neck:=min(neck,e[i].flow);
           u:=j;
           if u=t then
           begin
             ans:=ans+neck;
             if ans>inf then exit;
             while u<> do
             begin
               u:=pre[u];
               j:=cur[u];
               e[j].flow:=e[j].flow-neck;
               e[j xor ].flow:=e[j xor ].flow+neck;
             end;
             neck:=inf;
           end;
           break;
         end;
         i:=e[i].next;
       end;
       if i=- then
       begin
         dec(numh[h[u]]);
         if numh[h[u]]= then exit;
         tmp:=t;
         q:=-;
         i:=p[u];
         while i<>- do
         begin
           j:=e[i].po;
           if e[i].flow> then
             if tmp>h[j] then
             begin
               tmp:=h[j];
               q:=i;
             end;
           i:=e[i].next;
         end;
         h[u]:=tmp+;
         inc(numh[h[u]]);
         cur[u]:=q;
         if u<> then
         begin
           u:=pre[u];
           neck:=d[u];
         end;
       end;
     end;
   end;

 begin
   readln(n,m);
   for i:= to m do
   begin
     readln(x,y,z,b);
     add(x,y,z,b);
   end;
   len:=-;
   fillchar(p,sizeof(p),);
   readln(m1,t);
   inc(t);
   for i:= to t- do
     if i mod = then
     begin
       ins(i,t,calc(i));
       ins(t,i,);
     end
     else begin
       ins(,i,calc(i));
       ins(i,,);
     end;

   for i:= to m1 do
   begin
     readln(x,y);
     ins(x,y,inf);
     ins(y,x,);
   end;
   sap;
   if ans>inf then writeln(-)
   else writeln(ans::);
 end.