【BZOJ1179】[Apio2009]Atm (tarjan+SPFA)

显而易见的tarjan+spfa...不解释了

 const maxn=;
 type
  edgetype=record
   toward,next:longint;
  end;

 var
  edge1,edge2:array[..maxn] of edgetype;
  first1,first2,scc,stack,dfn,low,val,sum,q,d:Array[..maxn] of longint;
  pd:array[..maxn] of boolean;
  num,tot,n,m,cnt,top:longint;

 function min(x,y:longint):longint; begin if x<y then exit(x) else exit(y); end;

 procedure addedge(i,j:longint);
 begin
  inc(tot);
  edge1[tot].toward:=j;
  edge1[tot].next:=first1[i];
  first1[i]:=tot;
 end;

 procedure add(i,j:longint);
 begin
  inc(tot);
  edge2[tot].toward:=j;
  edge2[tot].next:=first2[i];
  first2[i]:=tot;
 end;

 procedure tarjan(v:longint);
 var i,tmp,u:longint;
 begin
  inc(cnt); dfn[v]:=cnt; low[v]:=cnt;
  inc(top); stack[top]:=v;
  pd[v]:=true; i:=first1[v];
  while i<> do
   begin
    tmp:=edge1[i].toward;
    if dfn[tmp]= then
     begin
      tarjan(tmp);
      low[v]:=min(low[v],low[tmp]);
     end
    else if pd[tmp] then low[v]:=min(low[v],dfn[tmp]);
    i:=edge1[i].next;
   end;
  if low[v]=dfn[v] then
   begin
    inc(num);
    repeat
     u:=stack[top]; dec(top);
     pd[u]:=false; scc[u]:=num;
     inc(sum[num],val[u]);
    until u=v;
   end;
 end;

 procedure spfa(s:longint);
 var head,tail,i,j,tmp:longint;
 begin
  fillchar(d,sizeof(d),);
  fillchar(pd,sizeof(pd),false);
  head:=;
  tail:=;
  pd[scc[s]]:=true;
  q[]:=scc[s];
  d[scc[s]]:=sum[scc[s]];
  while head<>tail do
   begin
    inc(head);
    if head>maxn then head:=;
    j:=q[head];
    i:=first2[j];
    while i<> do
     begin
      tmp:=edge2[i].toward;
      if d[j]+sum[tmp]>d[tmp] then
       begin
        d[tmp]:=d[j]+sum[tmp];
        if not pd[tmp] then
         begin
          inc(tail); if tail>maxn then tail:=;
          q[tail]:=tmp;
          pd[tmp]:=true;
         end;
       end;
      i:=edge2[i].next;
     end;
    pd[j]:=false;
   end;
 end;

 procedure init;
 var i,j,a,b:longint;
 begin
  read(n,m);
  for i:=  to m do
   begin
    readln(a,b);
    addedge(a,b);
   end;
  for i:=  to n do read(val[i]);
  for i:=  to n do if dfn[i]= then tarjan(i);
 end;

 procedure solve;
 var p,x,ans,s,i,j:longint;
 begin
  read(s,p);
  tot:=;
  for j:=  to n do
   begin
    i:=first1[j];
    while i<> do
     begin
      x:=edge1[i].toward;
      if scc[x]<>scc[j] then add(scc[j],scc[x]);
      i:=edge1[i].next;
     end;
   end;
  spfa(s);
  ans:=;
  for i:=  to p do
   begin
    read(x);
    if d[scc[x]]>ans then ans:=d[scc[x]];
   end;
  writeln(ans);
 end;

 Begin
  init;
  solve;
 End.