Data commit

Task/Brilliant-numbers/Delphi/brilliant-numbers.delphi

@@ -0,0 +1,75 @@
+function Compare(P1,P2: pointer): integer;
+{Compare for quick sort}
+begin
+Result:=Integer(P1)-Integer(P2);
+end;
+
+procedure GetBrilliantNumbers(List: TList; Limit: integer);
+{Return specified number of Brilliant Numbers in list}
+var I,J,P,Stop: integer;
+var Sieve: TPrimeSieve;
+begin
+Sieve:=TPrimeSieve.Create;
+try
+{build twices as many primes}
+Sieve.Intialize(Limit*2);
+{Pair every n-digt prime with every n-digit prime}
+I:=2;
+while true do
+	begin
+	J:=I;
+	{Put primes in J up to next power of 10 - 1}
+	Stop:=Trunc(Power(10,Trunc(Log10(I))+1));
+	while J<Stop do
+		begin
+		{Get the product}
+		P:=I * J;
+		{and store in the list}
+		List.Add(Pointer(P));
+		{Exit if we have all the numbers}
+		if List.Count>=Limit then break;
+		{Get next prime}
+		J:=Sieve.NextPrime(J);
+		end;
+	{break out of outer loop if done}
+	if List.Count>=Limit then break;
+	{Get next prime}
+	I:=Sieve.NextPrime(I);
+	end;
+{The list won't be in order, so sort them}
+List.Sort(Compare);
+finally Sieve.Free; end;
+end;
+
+
+procedure ShowBrilliantNumbers(Memo: TMemo);
+var List: TList;
+var S: string;
+var I,D,P: integer;
+begin
+List:=TList.Create;
+try
+{Get 10 million brilliant numbers}
+GetBrilliantNumbers(List,1000000);
+{Show the first 100}
+S:='';
+for I:=0 to 100-1 do
+	begin
+	S:=S+Format('%7d',[Integer(List[I])]);
+	if (I mod 10)=9 then S:=S+CRLF;
+	end;
+Memo.Lines.Add(S);
+{Show additional information}
+for D:=1 to 8 do
+	begin
+	P:=Trunc(Power(10,D));
+	{Scan to find for 1st brilliant number >= 10^D }
+	for I:=0 to List.Count-1 do
+	 if Integer(List[I])>=P then break;
+	{Display the info}
+	S:=Format('First brilliant number >= 10^%d is %10d',[D,Integer(List[I])]);
+	S:=S+Format(' at position %10D', [I]);
+	Memo.Lines.Add(S);
+	end;
+finally List.Free; end;
+end;