BZOJ 2243：染色（树链剖分+区间合并线段树）

program putcolor;
type
  thing=record
     l,r,v,s,e:longint;
  end;
  point=^node;
    node=record
     x:longint; next:point;
  end;
var
  a:array[0..100000]of point;
  dat:array[0..400000]of thing;
  sz,son,id,fa,v,b,d,top:array[0..100000]of longint;
  n,i,m,len:longint;
procedure add(x,y:longint);
var p:point;
begin
  new(p); p^.x:=y; p^.next:=a[x]; a[x]:=p;
end;
procedure swap(var x,y:longint);
var t:longint;
begin
  t:=x; x:=y; y:=t;
end;
procedure dfs1(x:longint);
var y:longint; p:point;
begin
  new(p); p:=a[x]; sz[x]:=1;
  while p<>nil do
   begin
     if p^.x=fa[x] then begin p:=p^.next; continue; end;
     y:=p^.x; fa[y]:=x; d[y]:=d[x]+1;
     dfs1(y);
     inc(sz[x],sz[y]); if sz[y]>sz[son[x]] then son[x]:=y;
     p:=p^.next;
   end;
end;
procedure dfs2(x,k:longint);
var i:longint; p:point;
begin
  inc(len); id[x]:=len; b[len]:=v[x]; top[x]:=k;
  if son[x]>0 then dfs2(son[x],k);
  new(p); p:=a[x];
  while p<>nil do
   begin
     if (p^.x<>fa[x])and(p^.x<>son[x]) then dfs2(p^.x,p^.x);
     p:=p^.next;
   end;
end;
procedure down(p,x,y:longint);
var l,r,v:longint;
begin
  if x=y then exit;
  l:=p*2; r:=p*2+1; v:=dat[p].e;
  dat[l].l:=v; dat[l].r:=v; dat[l].s:=1;dat[l].e:=v;
  dat[r].l:=v; dat[r].r:=v; dat[r].s:=1;dat[r].e:=v;
  dat[p].e:=-1;
end;
procedure update(p,x,y:longint);
var l,r:longint;
begin
  if x=y then exit;
  l:=p*2; r:=p*2+1;
  dat[p].l:=dat[l].l; dat[p].r:=dat[r].r;
  dat[p].s:=dat[l].s+dat[r].s;
  if dat[l].r=dat[r].l then dec(dat[p].s);
end;
procedure build(p,l,r:longint);
var mid:longint;
begin
  dat[p].s:=0;  dat[p].e:=-1;
  if l=r then exit;
  mid:=(l+r) div 2;
  build(p*2,l,mid); build(p*2+1,mid+1,r);
end;
procedure change(x,y,p,l,r,v:longint);
var mid:longint;
begin
  if dat[p].e>=0 then down(p,l,r);
  if (x<=l)and(r<=y) then
  begin dat[p].l:=v; dat[p].r:=v; dat[p].s:=1; dat[p].e:=v; end else
  begin
    mid:=(l+r) div 2;
    if x<=mid then  change(x,y,p*2,l,mid,v);
    if y>mid  then  change(x,y,p*2+1,mid+1,r,v);
    update(p,l,r);
  end;
end;
function query(x,y,p,l,r:longint):longint;
var mid,ans:longint;
begin
  if (x<=l)and(r<=y) then exit(dat[p].s)
  else
   begin
    mid:=(l+r) div 2;if dat[p].e>=0 then down(p,l,r);  ans:=0;
    if x<=mid then ans:=query(x,y,p*2,l,mid);
    if y>mid  then inc(ans,query(x,y,p*2+1,mid+1,r));
    if (x<=mid)and(y>mid) then
     if dat[p*2].r=dat[p*2+1].l then dec(ans);
    exit(ans);
   end;
end;
function get(p,l,r,x:longint):longint;
var mid:longint;
begin
  if dat[p].e>=0 then down(p,l,r);
  if l=x then exit(dat[p].l);
  mid:=(l+r) div 2;
  if x<=mid then exit(get(p*2,l,mid,x));
  if x>mid then exit(get(p*2+1,mid+1,r,x));
end;
procedure solvechange(x,y,z:longint);
var fx,fy,t,ans:longint;
begin
  fx:=top[x]; fy:=top[y]; ans:=0;
  while fx<>fy do
   begin
     if d[fx]<d[fy] then begin  swap(x,y);  swap(fx,fy);; end;
     change(id[fx],id[x],1,1,n,z);
     x:=fa[fx]; fx:=top[x];
   end;
  if d[x]>d[y] then swap(x,y);
  change(id[x],id[y],1,1,n,z);
end;
function solvequery(x,y:longint):longint;
var fx,fy,t,ans:longint;
begin
  fx:=top[x]; fy:=top[y]; ans:=0;
  while fx<>fy do
   begin
     if d[fx]<d[fy] then begin  swap(x,y); swap(fx,fy); end;
     inc(ans,query(id[fx],id[x],1,1,n));
     if get(1,1,n,id[fx])=get(1,1,n,id[fa[fx]]) then dec(ans);
     x:=fa[fx]; fx:=top[x];
   end;
  if d[x]>d[y] then swap(x,y);
  inc(ans,query(id[x],id[y],1,1,n));
  exit(ans);
end;
procedure solve;
var i,x,y,z:longint;  c:char;
begin
  build(1,1,n);
  for i:=1 to n do change(id[i],id[i],1,1,n,v[i]);
  for i:=1 to m do
   begin
     read(c);
     if c=‘C‘ then begin read(x,y,z);  solvechange(x,y,z); end
      else begin read(x,y); writeln(solvequery(x,y)); end;
     readln;
   end;
end;
procedure int;
var i,x,y:longint; p:point;
begin
  readln(n,m);
  for i:=1 to n do read(v[i]);
  for i:=1 to n-1 do
   begin
     readln(x,y);
     add(x,y); add(y,x);
   end;
end;
begin
  int;
  dfs1(1);dfs2(1,1);
  solve;
end.