POJ 3321：Apple Tree（dfs序+树状数组）

program apple;
type
  point=^node;
   node=record
     x:longint; next:point;
   end;
var
  a:array[0..100000]of point;
  bit:array[0..200000]of longint;
  b,v1,v2:array[0..100000]of longint;
  g:array[0..100000]of boolean;
  n,i,m,d,x,y:longint; c:char;
procedure add(x,y:longint);
var p:point;
begin
  new(p); p^.x:=y;  p^.next:=a[x]; a[x]:=p;
end;
procedure dfs(x:longint);
var p:point;
begin
  inc(d); v1[x]:=d; g[x]:=true; new(p); p:=a[x];
  while p<>nil do
   begin
     if g[p^.x]=false then dfs(p^.x); p:=p^.next;
   end;
  inc(d); v2[x]:=d;
end;
procedure change(x:longint);
var i,y:longint;
begin
  y:=x;
  if b[x]=0 then i:=1 else i:=-1;
  x:=v1[x];
  while (x<=2*n) do
   begin inc(bit[x],i); inc(x,x and (-x));end;
  b[y]:=1-b[y];
end;
function query(x:longint):longint;
var s:longint;
begin
  s:=0;
  while x>0 do
   begin inc(s,bit[x]); dec(x,x and (-x)); end;
  exit(s);
end;
begin
  readln(n);
  for i:=1 to n-1 do
   begin
     readln(x,y);
     add(x,y);  add(y,x);
   end;
  d:=0; dfs(1);
  for i:=1 to n do change(i);
  readln(m);
  for i:=1 to m do
   begin
     readln(c,x);
     if c=‘C‘ then change(x)
       else writeln(query(v2[x])-query(v1[x]-1));
   end;
 end.