Delphi随机生成不重复的数

procedure TForm1.Button1Click(Sender: TObject);
var
b: array of integer;
num: Integer; //随机数的个数
i, temp: integer;
begin
num := 10;
SetLength(b,num);
for i := 1 to num DO
b[i] := i;
ListBox1.Clear;
for i := 1 to num do
begin
temp := Random(num - i + 1) + 1;
ListBox1.Items.Add(IntToStr(b[temp]));
b[temp] := b[num - i + 1];
end;
end;