Сортировка простым слиянием, нужно помочь изменить кол-во файлов Опции

[cooler]

Нужна программа сортировки простым слиянием с 3-мя файлами .
По методичке сделал с двумя файлами, а вот как с 3-мя то сделать никак не разберусь.
Разбиение ещё более-менее понятно, а вот слияние


Программа также в архиве приложена

type
  TKey = Integer;
  TData = Array of TKey;

  TFormSimpleMerging = class(TForm)
    ChartMain: TChart;
    Panel1: TPanel;
    Panel2: TPanel;
    ButtoStartTest: TButton;
    Series1: TLineSeries;
    Panel3: TPanel;
    MemoData: TMemo;
    Label1: TLabel;
    Label2: TLabel;
    BitBtnSaveChartBmp: TBitBtn;
    SavePictureDialogChart: TSavePictureDialog;
    Series2: TLineSeries;
    SpinEditStep: TSpinEdit;
    SpinEditTestsCount: TSpinEdit;
    CheckBoxWorstData: TCheckBox;
    CheckBoxEnableAnimation: TCheckBox;
    procedure BitBtnSaveChartBmpClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure ButtoStartTestClick(Sender: TObject);
    procedure ResetChart(const GraphStep, Step, TestsCount: Integer);
    procedure FillRandomData(var DataFile: TFileStream; const Amount: Integer);
    procedure FillWorstData(var DataFile: TFileStream; const Amount: Integer);
    procedure PrintData(var DataFile: TFileStream; const Header: String);
    function SortSimpleMerging(var DataFile: TFileStream; const TempFilesCount: Byte): Cardinal;

  private
    DataSet: TData;
    DataFile: TFileStream;
  public

  end;

var
  FormSimpleMerging: TFormSimpleMerging;

implementation

{$R *.dfm}

procedure TFormSimpleMerging.ButtoStartTestClick(Sender: TObject);
var
  Step, TestsCount, i, Iterations: Integer;
begin
  Step:= SpinEditStep.Value;
  TestsCount:= SpinEditTestsCount.Value;

  ResetChart(1,Step,TestsCount);

  ChartMain.Series[0].AddXY(0,0);

//  FillRandomData(DataFile,100);

//  PrintData(DataFile,'Ïðîâåðî÷êà');

  for i:= 1 to TestsCount do
  begin
    if CheckBoxWorstData.Checked then
      FillWorstData(DataFile,Step*i)
    else
      FillRandomData(DataFile,Step*i);

//    PrintData(DataFile,'Èñõîäíûé íàáîð äàííûõ:');
    Iterations:= SortSimpleMerging(DataFile,2);


//    PrintData(DataFile,'Óïîðÿäî÷åííûé íàáîð äàííûõ:');
    MemoData.Lines.Add('Êîëè÷åñòâî îïåðàöèé: '+IntToStr(Iterations));

    ChartMain.Series[0].AddXY(Step*i,Iterations);
    if CheckBoxEnableAnimation.Checked then
      ChartMain.Refresh;
  end;

end;

procedure TFormSimpleMerging.FormCreate(Sender: TObject);
var
  GraphStep, Step, TestsCount: Integer;
begin
  Step:= SpinEditStep.Value;
  TestsCount:= SpinEditTestsCount.Value;
  
  ResetChart(1,Step,TestsCount);

  DataFile:= TFileStream.Create('TestFile.txt',fmCreate,fmShareDenyWrite);
end;

procedure TFormSimpleMerging.ResetChart(const GraphStep, Step, TestsCount: Integer);
var
  i, N: Integer;
  O: Extended;
  SeriesFunction: TLineSeries;
begin
  ChartMain.Series[0].Clear;
  ChartMain.Series[1].Clear;
  ChartMain.Refresh;

  ChartMain.Series[1].AddXY(0,0);
  N:= 1;
  While (N <= Step*TestsCount) do
  begin
    O:= Log2(N);
    ChartMain.Series[1].AddXY(N,O);
    N:= N + GraphStep;
  end;
end;

procedure TFormSimpleMerging.FillRandomData(var DataFile: TFileStream; const Amount: Integer);
var
  Buffer: TKey;
  i: Integer;
begin
  Randomize;
  DataFile.Seek($0,soFromBeginning);
  for i:= 0 to Amount-1 do
  begin
    Buffer:= Random(Amount*10);
    DataFile.Write(Buffer,SizeOf(Buffer));
  end;
end;

procedure TFormSimpleMerging.FillWorstData(var DataFile: TFileStream; const Amount: Integer);
var
  Buffer: TKey;
  i: Integer;
begin
  Randomize;
  DataFile.Seek($0,soFromBeginning);
  for i:= 0 to Amount-1 do
  begin
    Buffer:= Amount-i;
    DataFile.Write(Buffer,SizeOf(Buffer));
  end;
end;

procedure TFormSimpleMerging.PrintData(var DataFile: TFileStream; const Header: String);
var
  Buffer: TKey;
  i: Integer;
  Str: String;
begin
  Str:= '';
  DataFile.Seek($0,soFromBeginning);
  for i:= 0 to (DataFile.Size div SizeOf(Buffer)) - 1 do
  begin
    DataFile.Read(Buffer,SizeOf(Buffer));
    Str:= Str + IntToStr(Buffer) + '; ';
  end;
  MemoData.Lines.Add(Header);
  MemoData.Lines.Add(Str);
end;

function TFormSimpleMerging.SortSimpleMerging(var DataFile: TFileStream; const TempFilesCount: Byte): Cardinal;
var
  TempFiles: Array of TFilestream;
  Buffer, Buffer2: TKey;
  i, k, KeysToRead, CurFile, FileSwitch: Integer;
  RecordsCount, j, Iterations: Cardinal;
  Limits: Array of Word;
  Str: String;
begin
  SetLength(TempFiles,TempFilesCount);
  SetLength(Limits,TempFilesCount);
  RecordsCount:= DataFile.Size div SizeOf(TKey);
  Iterations:= 0;
  for i:= 0 to TempFilesCount - 1 do
  begin
    TempFiles[i]:= TFileStream.Create('TempFile'+IntToStr(i+1)+'.txt',fmCreate,fmShareDenyWrite);
  end;

  // Îñíîâíîé öèêë ñîðòèðîâêè
  KeysToRead:= 1;
  for i:= 0 to Ceil(LogN(TempFilesCount,RecordsCount))-1 do
  begin
    Inc(Iterations);
    // Ðàçáèåíèå ôàéëà âî âñïîìîãàòåëüíûå
    CurFile:= 0;
    FileSwitch:= 0;
    Str:= '';
    DataFile.Seek($0,soFromBeginning);
    for j:= 0 to TempFilesCount - 1 do
    begin
      TempFiles[j].Size:= 0;
      TempFiles[j].Seek($0,soFromBeginning);
    end;

    for j:= 0 to RecordsCount - 1 do
    begin
//      Str:= Str + IntToStr(CurFile) + '; ';
      DataFile.Read(Buffer,SizeOf(Buffer));
      TempFiles[CurFile].Write(Buffer,SizeOf(Buffer));
      Inc(FileSwitch);
//      Inc(Iterations,2);

      if (FileSwitch = KeysToRead) then
      begin
        FileSwitch:= 0;
        if (CurFile < TempFilesCount - 1) then
          Inc(CurFile)
        else
          CurFile:= 0;
      end;
    end;

//    PrintData(TempFiles[0],'Ôàéë 1');
//    PrintData(TempFiles[1],'Ôàéë 2');
//    MemoData.Lines.Add(Str);
    // Îáðàòíîå ñëèÿíèå
    CurFile:= 0;
    FileSwitch:= 0;
    Str:= '';
    DataFile.Seek($0,soFromBeginning);
    for j:= 0 to TempFilesCount - 1 do
      TempFiles[j].Seek($0,soFromBeginning);

    TempFiles[0].Read(Buffer,SizeOf(Buffer));
//    Inc(Iterations);
    if (KeysToRead <= TempFiles[0].Size div SizeOf(Buffer)) then
      Limits[0]:= KeysToRead
    else
      Limits[0]:= TempFiles[0].Size div SizeOf(Buffer);
    TempFiles[1].Read(Buffer2,SizeOf(Buffer2));
//    Inc(Iterations);
    if (KeysToRead <= TempFiles[1].Size div SizeOf(Buffer2)) then
      Limits[1]:= KeysToRead
    else
      Limits[1]:= TempFiles[1].Size div SizeOf(Buffer2);
    for j:= 0 to RecordsCount - 1 do
    begin
      if (Limits[1] = 0)
       or (Buffer < Buffer2) and (Limits[0] > 0) then
      begin
        DataFile.Write(Buffer,SizeOf(Buffer));
        TempFiles[0].Read(Buffer,SizeOf(Buffer));
        Dec(Limits[0]);
//        Inc(Iterations,2);
      end
      else
      begin
        DataFile.Write(Buffer2,SizeOf(Buffer2));
        TempFiles[1].Read(Buffer2,SizeOf(Buffer2));
        Dec(Limits[1]);
//        Inc(Iterations,2);
      end;
      if (Limits[0] = 0) and (Limits[1] = 0) then
      begin
        if (TempFiles[0].Position < TempFiles[0].Size + 1) then
          Limits[0]:= KeysToRead;
        if (TempFiles[1].Position < TempFiles[1].Size + 1) then
          Limits[1]:= KeysToRead;
      end;
    end;
//    PrintData(DataFile,'Îñíîâíîé ôàéë');
//    MemoData.Lines.Add('');
    KeysToRead:= KeysToRead * 2;
  end;
  for i:= 0 to TempFilesCount - 1 do
  begin
    TempFiles[i].Destroy;
  end;
  Result:= Iterations;
end;



procedure TFormSimpleMerging.BitBtnSaveChartBmpClick(Sender: TObject);
begin
  if SavePictureDialogChart.Execute then
  begin
    ChartMain.SaveToBitmapFile(SavePictureDialogChart.FileName);
  end;
end;

end.