bzoj2427

一开始读错题导致各种不会做，无奈
其实是一道水题，缩点反向建图树形dp即可

type link=^point;
     point=record
       po:longint;
       next:link;
     end;

var dfn,low,st,w,be,v,c:array[0..2010] of longint;
    e:array[0..1010] of link;
    fa,vis,f:array[0..1010] of boolean;
    dp:array[0..210,0..2010,0..2] of longint;
    y,s,h,t,ans,i,j,n,m,x:longint;
    ch:boolean;

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

function max(a,b:longint):longint;
  begin
    if a>b then exit(a) else exit(b);
  end;

procedure add(x,y:longint);
  var p:link;
  begin
    new(p);
    p^.po:=y;
    p^.next:=e[x];
    e[x]:=p;
  end;

procedure tarjan(x:longint);
  var y,r:longint;
      p:link;
  begin
    inc(h);
    dfn[x]:=h;
    low[x]:=h;
    vis[x]:=true;
    f[x]:=true;
    inc(t);
    st[t]:=x;
    p:=e[x];
    while p<>nil do
    begin
      y:=p^.po;
      if not vis[y] then
      begin
        tarjan(y);
        low[x]:=min(low[x],low[y]);
      end
      else if f[y] then low[x]:=min(low[x],low[y]);
      p:=p^.next;
    end;
    if dfn[x]=low[x] then
    begin
      while st[t+1]<>x do
      begin
        r:=st[t];
        be[r]:=x;
        f[r]:=false;
        dec(t);
      end;
    end;
  end;

procedure treedp(x:longint);
  var y,i,j,k:longint;
      p:link;
  begin
    p:=e[x];
    dp[x,w[x],0]:=v[x];
    k:=0;
    while p<>nil do
    begin
      y:=p^.po;
      treedp(y);
      k:=1-k;
      for i:=0 to m do
        dp[x,i,k]:=dp[x,i,1-k];
      for i:=0 to m-w[x] do
        if dp[y,i,1]>0 then
        begin
          for j:=w[x] to m-i do
            dp[x,j+i,k]:=max(dp[x,j+i,k],dp[x,j,1-k]+dp[y,i,1]);
        end;
      p:=p^.next;
    end;
    if k=0 then
      for i:=0 to m do
         dp[x,i,1]:=dp[x,i,0];
  end;

begin
  readln(n,m);
  for i:=1 to n do
    read(w[i]);
  for i:=1 to n do
    read(v[i]);
  for i:=1 to n do
  begin
    read(c[i]);
    if c[i]<>0 then add(i,c[i]);
  end;
  for i:=1 to n do
    if not vis[i] then
    begin
      h:=0;
      t:=0;
      tarjan(i);
    end;

  for i:=1 to n do
  begin
    if be[i]<>i then
    begin
      inc(w[be[i]],w[i]);
      inc(v[be[i]],v[i]);
    end;
    e[i]:=nil;
  end;
  for i:=1 to n do
    if be[i]=i then
    begin
      if (be[c[i]]=i) or (c[i]=0) then add(0,i)
      else add(be[c[i]],i);
    end;
  ans:=0;
  v[0]:=0;
  w[0]:=0;
  treedp(0);
  for i:=1 to m do
    ans:=max(ans,dp[0,i,1]);
  writeln(ans);
end.