虚树模板

稍微贴个建立虚树的子过程……我觉得我写的还挺清晰的

procedure solve;
var k,i,ff,x:longint;
begin
  readln(k);
  for i:=1 to k do
  begin
    read(h[i]);bo[h[i]]:=true;
  end;
  qsort(1,k);
  top:=1;st[top]:=1;ttt:=0;
  for i:=1 to k do
  begin
    x:=h[i];
    if x=st[top] then continue;
    ff:=lca(x,st[top]);
    while (dep[ff]<dep[st[top-1]])and(top>1) do
    begin
      add2(st[top-1],st[top]);
      dec(top);
    end;
    if ff<>st[top] then add2(ff,st[top]);
    if st[top-1]<>ff then st[top]:=ff else dec(top);
    inc(top);st[top]:=x;
  end;
  while top>1 do
  begin
    add2(st[top-1],st[top]);
    dec(top);
  end;
  for i:=1 to k do bo[h[i]]:=false;
end;