Proper divisors: Difference between revisions

Version with TParallel.For

<lang Delphi>

program ProperDivisors;

{$APPTYPE CONSOLE}

{$R *.res}

uses

System.SysUtils,

System.Threading,

System.SyncObjs;

type

TProperDivisors = array of Integer;

function GetProperDivisors(const value: Integer): TProperDivisors;

var

i, count: Integer;

begin

count := 0;

for i := 1 to value div 2 do

begin

if value mod i = 0 then

begin

inc(count);

SetLength(result, count);

Result[count - 1] := i;

end;

end;

end;

procedure Println(values: TProperDivisors);

var

i: Integer;

begin

Write('[');

if Length(values) > 0 then

for i := 0 to High(values) do

Write(Format('%2d', [values[i]]));

Writeln(']');

end;

var

number, max_count, count, max_number: Integer;

begin

for number := 1 to 10 do

begin

write(number, ': ');

Println(GetProperDivisors(number));

end;

max_count := 0;

TParallel.for (1, 20000,

procedure(I: Int64)

begin

count := length(GetProperDivisors(I));

if count > max_count then

begin

TInterlocked.Exchange(max_count, count);

TInterlocked.Exchange(max_number, I);

end;

end);

Writeln(max_number, ': ', max_count);

readln;

end.

</lang>