Data commit

Task/Additive-primes/Delphi/additive-primes.delphi

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+{These routines would normally be in libraries but are shown here for clarity}
+
+
+function IsPrime(N: int64): boolean;
+{Fast, optimised prime test}
+var I,Stop: int64;
+begin
+if (N = 2) or (N=3) then Result:=true
+else if (n <= 1) or ((n mod 2) = 0) or ((n mod 3) = 0) then Result:= false
+else
+     begin
+     I:=5;
+     Stop:=Trunc(sqrt(N+0.0));
+     Result:=False;
+     while I<=Stop do
+           begin
+           if ((N mod I) = 0) or ((N mod (I + 2)) = 0) then exit;
+           Inc(I,6);
+           end;
+     Result:=True;
+     end;
+end;
+
+
+function SumDigits(N: integer): integer;
+{Sum the integers in a number}
+var T: integer;
+begin
+Result:=0;
+repeat
+	begin
+	T:=N mod 10;
+	N:=N div 10;
+	Result:=Result+T;
+	end
+until N<1;
+end;
+
+
+
+
+
+procedure ShowDigitSumPrime(Memo: TMemo);
+var N,Sum,Cnt: integer;
+var NS,S: string;
+begin
+Cnt:=0;
+S:='';
+for N:=1 to 500-1 do
+ if IsPrime(N) then
+	begin
+	Sum:=SumDigits(N);
+	if IsPrime(Sum) then
+		begin
+		Inc(Cnt);
+		S:=S+Format('%6d',[N]);
+		if (Cnt mod 8)=0 then S:=S+CRLF;
+		end;
+	end;
+Memo.Lines.Add(S);
+Memo.Lines.Add('Count = '+IntToStr(Cnt));
+end;