bzoj 1103: [POI2007]大都市meg （dfs序）

dfs序，加个bit维护前缀和就行了

 

type
  arr=record
    toward,next:longint;
  end;
const
  maxn=500005;
var
  edge:array[0..maxn]of arr;
  bit,numin,numout,first,deep:array[0..maxn]of longint;
  chose:array[0..maxn]of boolean;
  esum,tot,n,time:longint;
 
procedure addedge(j,k:longint);
begin
  inc(esum);
  edge[esum].toward:=k;
  edge[esum].next:=first[j];
  first[j]:=esum;
end;
 
procedure dfs(x:longint);
var
  i,too:longint;
begin
  inc(time);
  numin[x]:=time;
  chose[x]:=false;
  i:=first[x];
  while i>0 do begin
    too:=edge[i].toward;
    if chose[too] then begin
      deep[too]:=deep[x]+1;
      dfs(too);
    end;
    i:=edge[i].next;
  end;
  inc(time);
  numout[x]:=time;
end;
 
function lowbit(x:longint):longint;
begin
  exit(x and (-x));
end;
 
procedure add(x,y:longint);
begin
  while x<=n<<1 do begin
    inc(bit[x],y);
    inc(x,lowbit(x));
  end;
end;
 
function ask(x:longint):longint;
var
  ans:longint;
begin
  ans:=0;
  while x>=1 do begin
    inc(ans,bit[x]);
    dec(x,lowbit(x));
  end;
  exit(ans);
end;
 
procedure into;
var
  i,j,k:longint;
begin
  readln(n);
  for i:=1 to n-1 do begin
    readln(j,k);
    addedge(j,k);
    addedge(k,j);
  end;
  fillchar(chose,sizeof(chose),true);
  deep[1]:=1;
  dfs(1);
  //for i:=1 to n do writeln(i,' ',numin[i],' ',numout[i]);
  for i:=2 to n do begin
    add(numin[i],1);
    add(numout[i],-1);
  end;
end;
 
procedure work;
var
  i,j,m,k:longint;
  ch:char;
begin
  readln(m);
  while m>0 do begin
    read(ch);
    if ch='W' then begin
      dec(m);
      readln(j);
      writeln(ask(numin[j]));
    end
    else begin
      readln(j,k);
      if deep[j]<deep[k] then j:=k;
      add(numin[j],-1);
      add(numout[j],1);
    end;
  end;
end;
 
 
begin
  into;
  work;
end.