附有代码，生成随机不重复的数，如何得到生成最终的数aa，怎么显示呢？如果用ListBox1怎么显示？(5分)

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
ListBox1: TListBox;
Label1: TLabel;
Button2: TButton;
Button3: TButton;
Edit1: TEdit;
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}
var

aa : array[1..36] of string[2]; //aa数组为需要随机排列的数组，

procedure TForm1.FormCreate(Sender: TObject);

var

i,j:integer;

swapa:string[2];

begin

randomize;

for i:=1 to 36 do begin

j:=1+random(36);

swapa:=aa;

aa:=aa[j];

aa[j]:=swapa;

end; //由此得到不重复的随机排列数字

end;

procedure TForm1.Button1Click(Sender: TObject);

var

i,j:integer;

swapa:string[2];

begin

randomize;

for i:=1 to 36 do begin

j:=1+random(36);

swapa:=aa;

aa:=aa[j];

aa[j]:=swapa;

end; //由此得到不重复的随机排列数字



end;
附有代码，生成随机不重复的数，如何得到生成最终的数aa，怎么显示呢？如果用ListBox1怎么显示？

begin
for r:=0 to 50000 do
begin
edit1.text:='';
for i:=0 to 12 do
begin
Randomize;
//s sleep(1+random(9));
edit1.text:=edit1.text+inttostr(random(10));

end;
ListBox1.Items.Add(Edit1.Text)
end;

怎么样保证生成的东西不重复