Self-describing numbers: Difference between revisions

=={{header|Delphi}}==

{{works with|Delphi|6.0}}

{{libheader|SysUtils,StdCtrls}}

<syntaxhighlight lang="Delphi">

{This routine would normally be in a library. It is shown here for clarity.}

procedure GetDigitsRev(N: integer; var IA: TIntegerDynArray);

{Get an array of the integers in a number}

{Numbers returned from most to least significant}

var T,I,DC: integer;

begin

DC:=Trunc(Log10(N))+1;

SetLength(IA,DC);

for I:=DC-1 downto 0 do

begin

T:=N mod 10;

N:=N div 10;

IA[I]:=T;

end;

end;

function IsSelfDescribing(N: integer): boolean;

var IA: TIntegerDynArray;

var CA: array [0..9] of integer;

var I: integer;

begin

{Get digits, High-low order}

GetDigitsRev(N,IA);

for I:=0 to High(CA) do CA[I]:=0;

{Count number of each digit 0..9}

for I:=0 to High(IA) do

begin

CA[IA[I]]:=CA[IA[I]]+1;

end;

Result:=False;

{Compare original number with counts}

for I:=0 to High(IA) do

if IA[I]<>CA[I] then exit;

Result:=True;

end;

procedure SelfDescribingNumbers(Memo: TMemo);

var I: integer;

begin

for I:=0 to 100000000-1 do

if IsSelfDescribing(I) then

begin

Memo.Lines.Add(IntToStr(I));

end;

end;

</syntaxhighlight>

{{out}}

<pre>

1210

2020

21200

3211000

42101000

Elapsed Time: 23.584 Sec.

</pre>