Data commit

Task/Circular-primes/Delphi/circular-primes.delphi

@@ -0,0 +1,54 @@
+procedure ShowCircularPrimes(Memo: TMemo);
+{Show list of the first 19, cicular primes}
+var I,Cnt: integer;
+var S: string;
+
+
+
+	procedure RotateStr(var S: string);
+	{Rotate characters in string}
+	var I: integer;
+	var C: char;
+	begin
+	C:=S[Length(S)];
+	for I:=Length(S)-1 downto 1 do S[I+1]:=S[I];
+	S[1]:=C;
+	end;
+
+
+	function IsCircularPrime(N: integer): boolean;
+	{Test if all rotations of number are prime and}
+	{A rotation of the number hasn't been used before}
+	var I,P: integer;
+	var NS: string;
+	begin
+	Result:=False;
+	NS:=IntToStr(N);
+	for I:=1 to Length(NS)-1 do
+		begin
+		{Rotate string and convert to integer}
+		RotateStr(NS);
+		P:=StrToInt(NS);
+		{Exit if number is not prime or}
+		{Is prime, is less than N i.e. we've seen it before}
+		if not IsPrime(P) or (P<N) then exit;
+		end;
+	Result:=True;
+	end;
+
+begin
+S:='';
+Cnt:=0;
+{Look for circular primes and display 1st 19}
+for I:=0 to High(I) do
+ if IsPrime(I) then
+ if IsCircularPrime(I) then
+ 	begin
+	Inc(Cnt);
+	S:=S+Format('%7D',[I]);
+	if Cnt>=19 then break;
+	If (Cnt mod 5)=0 then S:=S+CRLF;
+	end;
+Memo.Lines.Add(S);
+Memo.Lines.Add('Count = '+IntToStr(Cnt));
+end;