bzoj 1503 郁闷的出纳员

Splay练手题，真正做起来不那么简单，虽然是简单的单点维护，但是删除的时候会比较恶心（吐槽一下，我就是因为一上来用这个题splay练手，调了半天没调出来，气死我了）。

友情提示：刚进公司就被开的不算在最后的答案里（这公司真冷酷......）

const
maxn=300000;
var
c:array[0..maxn,0..1]of longint;
fa,size,key:array[0..maxn]of longint;
n,i,a,limit,now,num,tot,sum,rot,tmp:longint;
sign:char;
procedure update(x:Longint);
begin
size[x]:=size[c[x,0]]+size[c[x,1]]+1;
end;

procedure rotate(var rot:longint;x:Longint);
var
y,z,p,q:longint;
begin
y:=fa[x]; z:=fa[y];
if c[y,0]=x then p:=0 else p:=1;
q:=p xor 1;
if y=rot then rot:=x else
if c[z,0]=y then c[z,0]:=x else c[z,1]:=x;
fa[x]:=z; fa[y]:=x; fa[c[x,q]]:=y;
c[y,p]:=c[x,q]; c[x,q]:=y;
update(y); update(x);
end;

procedure splay(var rot:longint;x:longint);
var
y,z:longint;
begin
while x<>rot do
begin
y:=fa[x]; z:=fa[y];
if y<>rot then
if (c[y,0]=x)xor(c[z,0]=y) then rotate(rot,x) else rotate(rot,y);
rotate(rot,x);
end;
end;

procedure insert(var t:longint; x,p:longint);
begin
if t=0 then
begin
inc(num);
t:=num;
key[t]:=x;
fa[t]:=p;
size[t]:=1;
splay(rot,t);
end
else
if x<key[t] then
insert(c[t,0],x,t)
else
insert(c[t,1],x,t);
end;

procedure delete(x:longint);
var
t,p:longint;
begin
p:=rot; t:=0;
while p>0 do
begin
if x<=key[p] then
begin
t:=p;
p:=c[p,0]
end
else
p:=c[p,1];
end;
if t=0 then
rot:=0
else
begin
splay(rot,t);
c[t,0]:=0;
fa[t]:=0;
update(t);
end;
end;

function find(t,k:longint):longint;
begin
if k>size[t] then exit(-1);
if size[c[t,1]]+1=k then exit(t);
if size[c[t,1]]+1>k then exit(find(c[t,1],k));
if size[c[t,1]]+1<k then exit(find(c[t,0],k-size[c[t,1]]-1));
end;

begin
//assign(input,'cashier.in'); reset(input);
//assign(output,'cashier.out'); rewrite(output);
readln(n,limit);
now:=0; rot:=0; num:=0;
for i:=1 to n do
begin
readln(sign,a);
case sign of
'I':
if a>=limit then
insert(rot,a-now,0);
'A':inc(now,a);
'S':
begin
dec(now,a);
delete(limit-now);
end;
'F':
begin
tmp:=find(rot,a);
if tmp=-1 then writeln(-1)
else writeln(key[tmp]+now);
end;
end;
end;
update(rot);
writeln(num-size[rot]);
//close(input);
//close(output);
end.