bzoj3572

通过这题我知道了一个鬼故事，trunc(ln(128)/ln(2))=6……以后不敢轻易这么写了

好了言归正传，这题明显的构建虚树，但构建虚树后怎么树形dp呢？

由于虚树上的点不仅是议事会还有可能是议事会的LCA，所以

我们要先求出虚树上每个点是被那个议事会管理的，这我们可以通过两遍dfs求出（儿子更新父亲，父亲更新儿子）

然后我们考虑虚树上每条边所代表原数的结点归属就可以了，这个地方细节比较多，建议自己想，具体见代码注释

 type node=record
        po,next:longint;
      end;
      point=record
        fr,ds:longint;
      end;

 var e:array[..] of node;
     f,b,c,d,a,st,ans,p,s:array[..] of longint;
     anc:array[..,..] of longint;
     w:array[..] of point;
     n,q,m,i,len,j,x,y,t,z:longint;
     v:array[..] of boolean;

 procedure swap(var a,b:longint);
   var c:longint;
   begin
     c:=a;
     a:=b;
     b:=c;
   end;

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

 procedure dfs(x:longint);
   var i,y:longint;
   begin
     inc(t);
     a[x]:=t;
     s[x]:=;
     i:=p[x];
     while i<> do
     begin
       y:=e[i].po;
       if s[y]= then
       begin
         anc[y,]:=x;
         d[y]:=d[x]+;
         dfs(y);
         s[x]:=s[x]+s[y];
       end;
       i:=e[i].next;
     end;
   end;

 procedure sort(l,r:longint);
   var i,j,x:longint;
   begin
     i:=l;
     j:=r;
     x:=c[(l+r) shr ];
     repeat
       while a[c[i]]<a[x] do inc(i);
       while a[x]<a[c[j]] do dec(j);
       if not(i>j) then
       begin
         swap(c[i],c[j]);
         inc(i);
         dec(j);
       end;
     until i>j;
     if l<j then sort(l,j);
     if i<r then sort(i,r);
   end;

 function lca(x,y:longint):longint;
   var i:longint;
   begin
     if x=y then exit(x);
     if d[x]<d[y] then swap(x,y);
     if d[x]>d[y] then
     begin
       for i:= downto  do
         if d[x]- shl i>=d[y] then x:=anc[x,i];
     end;
     if x=y then exit(x);
     for i:= downto  do
       if anc[x,i]<>anc[y,i] then
       begin
         x:=anc[x,i];
         y:=anc[y,i];
       end;
     exit(anc[x,]);
   end;

 procedure get(var a:point;x,y:longint);
   begin
     if (a.ds>x) or (a.ds=x) and (a.fr>y) then
     begin
       a.ds:=x;
       a.fr:=y;
     end;
   end;

 function find(x,h:longint):longint;
   var i:longint;
   begin
     if h= then exit(x);
     for i:= downto  do
       if h- shl i>= then
       begin
         x:=anc[x,i];
         h:=h- shl i;
         if h= then break;
       end;
     exit(x);
   end;

 procedure work1(x:longint);
   var i,y:longint;
   begin
     if v[x] then
     begin
       w[x].fr:=x;
       w[x].ds:=;
     end
     else begin
       w[x].fr:=n+;
       w[x].ds:=;
     end;
     f[x]:=s[x];
     i:=p[x];
     while i<> do
     begin
       y:=e[i].po;
       f[x]:=f[x]-s[find(y,d[y]-d[x]-)];
       work1(y);
       get(w[x],w[y].ds+d[y]-d[x],w[y].fr);
       i:=e[i].next;
     end;
   end;

 procedure work2(x:longint);
   var i,y:longint;
   begin
     i:=p[x];
     while i<> do
     begin
       y:=e[i].po;
       get(w[y],w[x].ds+d[y]-d[x],w[x].fr);
       work2(y);
       i:=e[i].next;
     end;
   end;

 procedure calc(x:longint);
   var i,y,l,h:longint;
   begin
     inc(ans[b[w[x].fr]],f[x]);  //我们先单独考虑边的端点
     i:=p[x];
     while i<> do
     begin
       y:=e[i].po;
       if w[x].fr=w[y].fr then
         inc(ans[b[w[x].fr]],s[find(y,d[y]-d[x]-)]-s[y])
       else begin
         l:=w[x].ds+w[y].ds+d[y]-d[x];
         h:=l div -w[y].ds;  //均分
         if (l mod =) and (w[x].fr<w[y].fr) then dec(h);  //注意临界情况
         h:=find(y,h);  //寻找向上d个单位的点
         inc(ans[b[w[x].fr]],s[find(y,d[y]-d[x]-)]-s[h]);  //注意这里的结点归属
         inc(ans[b[w[y].fr]],s[h]-s[y]);
       end;
       calc(y);
       i:=e[i].next;
     end;
     p[x]:=;
   end;

 begin
   readln(n);
   for i:= to n- do
   begin
     readln(x,y);
     add(x,y);
     add(y,x);
   end;
   dfs();
   for j:= to trunc(ln(n)/ln()) do
     for i:= to n do
     begin
       x:=anc[i,j-];
       anc[i,j]:=anc[x,j-];
     end;

   len:=;
   fillchar(p,sizeof(p),);
   readln(m);
   while m> do
   begin
     dec(m);
     len:=;
     readln(q);
     for i:= to q do
     begin
       read(c[i]);
       b[c[i]]:=i;
       v[c[i]]:=true;
     end;
     sort(,q);
     st[]:=;
     t:=;
     for i:= to q do
     begin
       x:=c[i];
       z:=lca(x,st[t]);
       while d[z]<d[st[t]] do
       begin
         if d[z]>=d[st[t-]] then
         begin
           add(z,st[t]);
           dec(t);
           if st[t]<>z then
           begin
             inc(t);
             st[t]:=z;
           end;
           break;
         end;
         add(st[t-],st[t]);
         dec(t);
       end;
       if st[t]<>x then
       begin
         inc(t);
         st[t]:=x;
       end;
     end;
     while t> do
     begin
       add(st[t-],st[t]);
       dec(t);
     end;
     work1();
     work2();
     calc();
     for i:= to q do
     begin
       write(ans[i],' ');
       ans[i]:=;
       b[c[i]]:=;
       v[c[i]]:=false;
     end;
     writeln;
   end;
 end.