Data commit

Task/Semiprime/Delphi/semiprime.delphi

@@ -0,0 +1,48 @@
+{This function would normally be in a library, but it shown here for clarity}
+
+procedure GetAllFactors(N: Integer;var IA: TIntegerDynArray);
+{Make a list of all irreducible factor of N}
+var I: integer;
+begin
+SetLength(IA,1);
+IA[0]:=1;
+for I:=2 to N do
+ while (N mod I)=0 do
+	begin
+	SetLength(IA,Length(IA)+1);
+	IA[High(IA)]:=I;
+	N:=N div I;
+	end;
+end;
+
+
+function IsSemiprime(N: integer): boolean;
+{Test if number is semiprime}
+var IA: TIntegerDynArray;
+begin
+{Get all factors of N}
+GetAllFactors(N,IA);
+Result:=False;
+{Since 1 is factor, ignore it}
+if Length(IA)<>3 then exit;
+Result:=IsPrime(IA[1]) and IsPrime(IA[2]);
+end;
+
+
+procedure Semiprimes(Memo: TMemo);
+var I,Cnt: integer;
+var S: string;
+begin
+Cnt:=0;
+S:='';
+{Test first 100 number to see if they are semiprime}
+for I:=0 to 100-1 do
+ if IsSemiprime(I) then
+	begin
+	Inc(Cnt);
+	S:=S+Format('%4d',[I]);
+	if (Cnt mod 10)= 0 then S:=S+CRLF;
+	end;
+Memo.Lines.Add(S);
+Memo.Lines.Add('Count='+IntToStr(Cnt));
+end;