hex.pas

   1 var
   2   i,n,k:longint;
   3   hex:string;
   4
   5 procedure jian(var hex:string; k:longint);
   6 var
   7   i,j:longint;
   8   s:set of char;
   9
  10 begin
  11   s:=[];
  12   for i:=1 to k-1 do s:=s+[hex[i]];
  13   for i:=k to length(hex) do
  14     begin
  15       if i>k then hex[i]:=succ('F');
  16       repeat
  17         hex[i]:=pred(hex[i]);
  18         if hex[i]=pred('A') then hex[i]:='9';
  19       until not(hex[i] in s);
  20       s:=s+[hex[i]];
  21     end;
  22 end;
  23
  24 begin
  25   readln(n);
  26   hex:='FEDCBA98';
  27   while n>1 do
  28     begin
  29       k:=1;
  30       for i:=1 to length(hex)-1 do k:=k*(16-i);
  31       i:=1;
  32       repeat
  33         if n>k then break;
  34         k:=k div (16-i);
  35         inc(i);
  36       until false;
  37       jian(hex,i);
  38       dec(n,k);
  39       if hex[1]='0' then delete(hex,1,1);
  40     end;
  41   writeln(hex);
  42 end.