算法模板——平衡树Treap 2

实现功能：同平衡树Treap 1（BZOJ3224 / tyvj1728）

这次的模板有了不少的改进，显然更加美观了，几乎每个部分都有了不少简化，尤其是删除部分，这个参照了hzwer神犇的写法，在此鸣谢，然后，贴模板走人

 var
    i,j,k,l,m,n,head,tot:longint;
    a,b,lef,rig,fix:array[..] of longint;
 function min(x,y:longint):longint;
          begin
               if x<y then min:=x else min:=y;
          end;
 function max(x,y:longint):longint;
          begin
               if x>y then max:=x else max:=y;
          end;
 procedure lt(var x:longint);
           var f,r:longint;
           begin
                if (x=) or (rig[x]=) then exit;
                b[rig[x]]:=b[x];b[x]:=b[lef[x]]+b[lef[rig[x]]]+;
                f:=x;r:=rig[x];
                rig[f]:=lef[r];
                lef[r]:=f;
                x:=r;
           end;
 procedure rt(var x:longint);
           var f,l:longint;
           begin
                if (x=) or (lef[x]=) then exit;
                b[lef[x]]:=b[x];b[x]:=b[rig[x]]+b[rig[lef[x]]]+;
                f:=x;l:=lef[x];
                lef[f]:=rig[l];
                rig[l]:=f;
                x:=l;
           end;
 function newp(x:longint):longint;
          begin
               inc(tot);newp:=tot;
               a[tot]:=x;b[tot]:=;
               lef[tot]:=;rig[tot]:=;
               fix[tot]:=random(maxlongint);
          end;
 procedure ins(var x:longint;y:longint);
           begin
                if x= then
                   begin
                        x:=newp(y);
                        exit;
                   end;
                if y<a[x] then
                   begin
                        ins(lef[x],y);b[x]:=b[lef[x]]+b[rig[x]]+;
                        if fix[lef[x]]<fix[x] then rt(x);
                   end
                else
                    begin
                         ins(rig[x],y);b[x]:=b[lef[x]]+b[rig[x]]+;
                         if fix[rig[x]]<fix[x] then lt(x);
                    end;
           end;
 procedure del(var x:longint;y:longint);
           begin
                if x= then exit;
                if a[x]=y then
                   begin
                        if lef[x]= then x:=rig[x] else
                        if rig[x]= then x:=lef[x] else
                        if fix[lef[x]]>fix[rig[x]] then
                           begin
                                lt(x);del(lef[x],y);
                                b[x]:=b[lef[x]]+b[rig[x]]+;
                           end
                        else
                            begin
                                 rt(x);del(rig[x],y);
                                 b[x]:=b[lef[x]]+b[rig[x]]+;
                            end;
                   end
                else if y<a[x] then
                     begin
                          del(lef[x],y);
                          b[x]:=b[lef[x]]+b[rig[x]]+;
                     end
                else begin
                          del(rig[x],y);
                          b[x]:=b[lef[x]]+b[rig[x]]+;
                     end;
           end;
 function getrank(x,y:longint):longint;
          begin
               if x= then exit();
               if y>a[x] then exit(b[lef[x]]++getrank(rig[x],y)) else exit(getrank(lef[x],y));
          end;
 function rankget(x,y:longint):longint;
          begin
               if y=(b[lef[x]]+) then exit(a[x]);
               if y<(b[lef[x]]+) then exit(rankget(lef[x],y)) else exit(rankget(rig[x],y--b[lef[x]]));
          end;
 function getpre(x,y:longint):longint;
          begin
               if x= then exit(-maxlongint);
               if a[x]<y then exit(max(a[x],getpre(rig[x],y))) else exit(getpre(lef[x],y));
          end;
 function getsuc(x,y:longint):longint;
          begin
               if x= then exit(maxlongint);
               if a[x]>y then exit(min(a[x],getsuc(lef[x],y))) else exit(getsuc(rig[x],y));
          end;
 begin
      readln(n);tot:=;head:=;
      for i:= to n do
          begin
               readln(j,k);
               case j of
                    :ins(head,k);
                    :del(head,k);
                    :writeln(getrank(head,k)+);
                    :writeln(rankget(head,k));
                    :writeln(getpre(head,k));
                    :writeln(getsuc(head,k));
               end;
          end;
 end.