unit BaumKlasseUnit;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.Generics.Collections,
  Vcl.ComCtrls;

type
  PNode = ^TNodeTest;

  TNodeTest = class
    private
      FDaten: String;
      FLinks: PNode;
      FRechts: PNode;
      FTreeNode: TTreeNode;
    public
      constructor Create;
  end;

  TForm4 = class(TForm)
    Lb_Ausgabe: TLabel;
    Ed_Eingabe: TEdit;
    Bt_Einfuegen: TButton;
    Bt_Links: TButton;
    Bt_Rechts: TButton;
    Bt_Loeschen: TButton;
    Bt_Wurzel: TButton;
    Bt_Aendern: TButton;
    Bt_NodeZaehlen: TButton;
    Bt_BlaetterZaehlen: TButton;
    Bt_Tiefe: TButton;
    TV: TTreeView;
    procedure FormCreate(Sender: TObject);
    procedure Bt_EinfuegenClick(Sender: TObject);
    procedure Bt_RechtsClick(Sender: TObject);
    procedure Bt_WurzelClick(Sender: TObject);
    procedure StatusBt;
    procedure Bt_LoeschenClick(Sender: TObject);
    procedure Bt_AendernClick(Sender: TObject);
    procedure Einfuegen(eingabe: String);
    procedure SetErgebnis(daten: TStringList);
    procedure Bt_NodeZaehlenClick(Sender: TObject);
    procedure Bt_BlaetterZaehlenClick(Sender: TObject);
    function GetErgebnis(): TStringList;
    function Durchgelaufen(): Boolean;
    function Hoehe(p: PNode): Integer;
    procedure Bt_TiefeClick(Sender: TObject);
    procedure Ed_EingabeKeyPress(Sender: TObject; var Key: Char);
    procedure TVMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure AktuallisiereMaus;
    procedure Bt_LinksClick(Sender: TObject);
    procedure EinzelnerKnotenLoeschen;
  private
    { Private-Deklarationen }
    {PWurzelNode: PNode;
    PStandNode: PNode;
    PParentNode: PNode;
    eingegeben, bearbeiten: Boolean;}
    PWurzelNode: PNode;
    PStandNode: PNode;
    PParentNode: PNode;
    eingegeben, bearbeiten: Boolean;
  public
    { Public-Deklarationen }
  end;

var
  Form4: TForm4;

implementation

{$R *.dfm}

constructor TNodeTest.Create;
begin
  inherited Create; //hierdurch wird der ursprüngliche Konstruktor aufgerufen
end;

procedure TForm4.Bt_AendernClick(Sender: TObject);
var
  eingabe: String;
begin
  if Tag = 0 then
  begin
    Ed_Eingabe.Text := PStandNode.FDaten;
    (Sender as TButton).Caption := 'Ändern (Reinschreiben)';
    Tag := 1;
    bearbeiten := True;
  end
  else if Tag = 1 then
  begin
    eingabe := Ed_Eingabe.Text;
    EinzelnerKnotenLoeschen;
    Einfuegen(eingabe);
    Ed_Eingabe.Text := '';
    (Sender as TButton).Caption := 'Ändern (Einlesen)';
    Tag := 0;
    bearbeiten := False;
  end;
end;

procedure TForm4.Bt_BlaetterZaehlenClick(Sender: TObject);
var
  Stack: TStack<PNode>;
  PBufferNode: PNode;
  i: Integer;
begin
  if PWurzelNode <> nil then
  begin
    Stack := TStack<PNode>.Create;
    i := 0;
    PBufferNode := PWurzelNode;
    if ((PWurzelNode.FLinks <> nil) and (PWurzelNode.FRechts <> nil)) then
    begin
      Stack.Push(PBufferNode);
      PBufferNode := PBufferNode.FLinks;
    end;
    if Stack.Count <> 0 then
    begin
      repeat
      begin
        if ((PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil)) then
        begin
          if (Stack.Count = 0) or (Stack.Peek <> PBufferNode) then
          begin
            Stack.Push(PBufferNode);
          end;
          PBufferNode := PBufferNode.FLinks;
        end
        else if PBufferNode.FRechts <> nil then
        begin
          PBufferNode := PBufferNode.FRechts;
        end
        else if PBufferNode.FLinks <> nil then
        begin
          PBufferNode := PBufferNode.FLinks;
        end
        else
        begin
          Inc(i);
          PBufferNode := Stack.Peek;
          Stack.Extract;
          Stack.TrimExcess;
          PBufferNode := PBufferNode.FRechts;
          if (PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil) then
          begin
            Stack.Push(PBufferNode);
          end;
        end;
      end;
      until Stack.Count = 0;
    end;
    if (PBufferNode.FLinks = nil) and (PBufferNode.FRechts = nil) then
    begin
      Inc(i);
    end;
    Stack.Clear;
    Stack.Free;
    if i = 1 then
    begin
      ShowMessage('Es gibt ' + IntToStr(i) + ' Blatt!');
    end
    else
    begin
      ShowMessage('Es gibt ' + IntToStr(i) + ' Blätter!');
    end;
  end;
end;

procedure TForm4.Bt_EinfuegenClick(Sender: TObject);
begin
  Einfuegen(Ed_Eingabe.Text);
  //TVEinfuegen(Ed_Eingabe.Text);
  Ed_Eingabe.Text := '';
  Ed_Eingabe.SetFocus;
end;

procedure TForm4.Ed_EingabeKeyPress(Sender: TObject; var Key: Char);
begin
  if Key = #13 then
  begin
    if bearbeiten then
    begin
      Bt_Aendern.Click;
    end
    else
    begin
      Bt_Einfuegen.Click;
    end;
    Key := #0; //Ist das nötig?
  end;
end;

procedure TForm4.Einfuegen;
var
  PCurrentNode: PNode;
  TCurrentNodeTest: TNodeTest;
  PBufferNode: PNode;
  durchlaufe: Boolean;
begin
//  PCurrentNode := nil;
  TCurrentNodeTest := TNodeTest.Create; //Neuer Node erzeugen
  New(PCurrentNode);
  PCurrentNode.FDaten := eingabe;
  PCurrentNode.FLinks := nil;
  PCurrentNode.FRechts := nil;
  PBufferNode := PWurzelNode;
  if PWurzelNode = nil then
  begin
    PWurzelNode := PCurrentNode;
    PWurzelNode.FTreeNode := TV.Items.AddChildObject(nil, 'Wurzel: ' + PWurzelNode.FDaten, PWurzelNode);
    PStandNode := PWurzelNode;
    Lb_Ausgabe.Caption := PWurzelNode.FDaten;
    Bt_Wurzel.Enabled := True;
  end
  else
  begin
    durchlaufe := True;
    while durchlaufe do
    begin
      if (eingabe <= PBufferNode.FDaten) and (PBufferNode.FLinks <> nil) then
      begin
        PBufferNode := PBufferNode.FLinks;
      end
      else if (eingabe > PBufferNode.FDaten) and (PBufferNode.FRechts <> nil) then
      begin
        PBufferNode := PBufferNode.FRechts;
      end
      else
      begin
        durchlaufe := False;
      end;
    end;
    if PBufferNode.FDaten >= eingabe then
    begin
      PCurrentNode.FTreeNode := TV.Items.AddChildObject(PBufferNode.FTreeNode, 'l: ' + PCurrentNode.FDaten, PCurrentNode);
      PBufferNode.FLinks := PCurrentNode;
    end
    else
    begin
      PCurrentNode.FTreeNode := TV.Items.AddChildObjectFirst(PBufferNode.FTreeNode, 'r: ' + PCurrentNode.FDaten, PCurrentNode);
      PBufferNode.FRechts := PCurrentNode;
    end;
  end;
  StatusBt;
  TV.FullExpand;
end;

procedure TForm4.Bt_LinksClick(Sender: TObject);
begin
  PStandNode.FTreeNode.Selected := False;
  PParentNode := PStandNode;
  PStandNode := PStandNode.FLinks;
  PStandNode.FTreeNode.Selected := True;
  Lb_Ausgabe.Caption := PStandNode.FDaten;
  StatusBt;
end;

procedure TForm4.Bt_LoeschenClick(Sender: TObject);
var
  BufferStack: TStack<PNode>;
  Stack: TStack<PNode>;
  PBufferNode: PNode;
  rl: Char;
begin
  if PStandNode = PWurzelNode then
  begin
    ShowMessage('Du kannst die Wurzel nicht löschen!');
  end
  else
  begin
    PBufferNode := PParentNode;
    if (PStandNode.FLinks <> nil) or (PStandNode.FRechts <> nil) then
    begin
      if MessageBox(Handle,'Ganzer Teilbaum löschen?','Bestätigen',MB_YESNO) = IDNO then
      begin
        if MessageBox(Handle, 'Einzelner Knoten löschen?', 'Bestätigen', MB_YESNO) = IDYES then
        begin
          //Methode zum löschen des einzelnen Knotens
          EinzelnerKnotenLoeschen;
          Exit;
        end;
        MessageDlg('Löschen wurde abgebrochen!', mtInformation,[mbOk], 0, mbOk);
        Exit;
      end;
    end;
    if PParentNode.FLinks = PStandNode then
    begin
      rl := 'l';
    end
    else if PParentNode.FRechts = PStandNode then
    begin
      rl := 'r';
    end;
    if ((PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil)) then
    begin
      BufferStack := TStack<PNode>.Create;
      Stack := TStack<PNode>.Create;
      BufferStack.Push(PStandNode);
      Stack.Push(PStandNode);
      PStandNode := PStandNode.FLinks;
      BufferStack.Push(PStandNode);
      if Stack.Count <> 0 then
      begin
        repeat
        begin
          if ((PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil)) then
          begin
            if Stack.Peek <> PStandNode then
            begin
              Stack.Push(PStandNode);
            end;
            PStandNode := PStandNode.FLinks;
          end
          else if PStandNode.FRechts <> nil then
          begin
            PStandNode := PStandNode.FRechts;
          end
          else if PStandNode.FLinks <> nil then
          begin
            PStandNode := PStandNode.FLinks;
          end
          else
          begin
            PStandNode := Stack.Peek;
            Stack.Extract;
            Stack.TrimExcess;
            PStandNode := PStandNode.FRechts;
            if (PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil) then
            begin
              Stack.Push(PStandNode);
            end;
          end;
          BufferStack.Push(PStandNode);
        end;
        until Stack.Count = 0;
      end;
      Stack.Clear;
      Stack.Free;
      while BufferStack.Count <> 0 do
      begin
        //Nehme aus BufferStack und lösche (+TTreeView)
        PStandNode := BufferStack.Peek;
        BufferStack.Extract;
        BufferStack.TrimExcess;
        TV.Items.Delete(PStandNode.FTreeNode);
        PStandNode.FTreeNode := nil;
        PStandNode.Flinks := nil;
        PStandNode.Frechts := nil;
        FreeAndNil(PStandNode);
      end;
      BufferStack.Clear;
      BufferStack.Free;
    end;
    if (PBufferNode.FLinks <> nil) and (rl = 'l') then
    begin
      if PBufferNode.FLinks.FDaten = '' then
      begin
        PBufferNode.FLinks := nil;
      end
      else
      begin
        PBufferNode.FTreeNode.Selected := False;
        TV.Items.Delete(PBufferNode.FLinks.FTreeNode);
        PBufferNode.FLinks.FTreeNode := nil;
        PBufferNode.FLinks.FLinks := nil;
        PBufferNode.FLinks.FRechts := nil;
        FreeAndNil(PBufferNode.FLinks);
        PBufferNode.FLinks := nil;
      end;
    end;
    if (PBufferNode.FRechts <> nil) and (rl = 'r') then
    begin
      if PBufferNode.FRechts.FDaten = '' then
      begin
        PBufferNode.FRechts := nil;
      end
      else
      begin
        PBufferNode.FTreeNode.Selected := False;
        TV.Items.Delete(PBufferNode.FRechts.FTreeNode);
        PBufferNode.FRechts.FTreeNode := nil;
        PBufferNode.FRechts.FLinks := nil;
        PBufferNode.FRechts.FRechts := nil;
        FreeAndNil(PBufferNode.FRechts);
        PBufferNode.FRechts := nil;
      end;
    end;
    PStandNode := PWurzelNode;
    PStandNode.FTreeNode.Selected := True;
    Lb_Ausgabe.Caption := PStandNode.FDaten;
    StatusBt;
  end;
end;


{begin
  if PStandNode = PParentNode.rechts then
  begin
    TV.Items.Delete(PStandNode.TreeNode);
    PStandNode.TreeNode := nil;
    PParentNode.rechts := nil;
  end
  else if PStandNode = PParentNode.links then
  begin
    PParentNode.links := nil;
    TV.Items.Delete(PStandNode.TreeNode);
    PStandNode.TreeNode := nil;
  end;
  if (PParentNode = PWurzelNode) or not ((PParentNode.rechts = nil) and (PParentNode.links = nil)) then
  begin
    Dec(BlaetterZaehlen);
  end;
  FreeAndNil(PStandNode);
  PStandNode := PWurzelNode;
  Lb_Ausgabe.Caption := PStandNode.daten;
  StatusBt;
  Dec(NodeZaehlen);
end;       }

procedure TForm4.EinzelnerKnotenLoeschen;
var
  rl: Char;
  PStandBufferNode: PNode;
  TStandBufferNode: TNodeTest;
  BufferStack: TStack<PNode>;
  Stack: TStack<PNode>;
  BufferTextStack: TStack<String>;
begin
  TStandBufferNode := TNodeTest.Create;
  PStandBufferNode.FRechts := PStandNode.FRechts;
  PStandBufferNode.FLinks := PStandNode.FLinks;
  if PStandNode = PParentNode.FLinks then
  begin
    rl := 'l';
  end
  else if PStandNode = PParentNode.FRechts then
  begin
    rl := 'r';
  end;
  if rl = 'r' then
  begin
    PStandNode := PStandNode.FLinks;
  end
  else if rl = 'l' then
  begin
    PStandNode := PStandNode.FRechts;
  end;
  if (PStandNode.FLinks = nil) or (PStandNode.FRechts = nil) then
  begin
    BufferTextStack := TStack<String>.Create;
    BufferTextStack.Push(PStandNode.FDaten);
  end
  else if ((PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil)) then
  begin
    BufferStack := TStack<PNode>.Create;
    BufferTextStack := TStack<String>.Create;
    Stack := TStack<PNode>.Create;
    BufferStack.Push(PStandNode);
    BufferTextStack.Push(PStandNode.FDaten);
    Stack.Push(PStandNode);
    PStandNode := PStandNode.FLinks;
    BufferStack.Push(PStandNode);
    BufferTextStack.Push(PStandNode.FDaten);
    if Stack.Count <> 0 then
    begin
      repeat
      begin
        if ((PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil)) then
        begin
          if Stack.Peek <> PStandNode then
          begin
            Stack.Push(PStandNode);
          end;
          PStandNode := PStandNode.FLinks;
        end
        else if PStandNode.FRechts <> nil then
        begin
          PStandNode := PStandNode.FRechts;
        end
        else if PStandNode.FLinks <> nil then
        begin
          PStandNode := PStandNode.FLinks;
        end
        else
        begin
          PStandNode := Stack.Peek;
          Stack.Extract;
          Stack.TrimExcess;
          PStandNode := PStandNode.FRechts;
          if (PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil) then
          begin
            Stack.Push(PStandNode);
          end;
        end;
        BufferStack.Push(PStandNode);
        BufferTextStack.Push(PStandNode.FDaten);
      end;
      until Stack.Count = 0;
    end;
    Stack.Clear;
    Stack.Free;
    while BufferStack.Count <> 0 do
    begin
      //Nehme aus BufferStack und lösche (+TTreeView)
      PStandNode := BufferStack.Peek;
      BufferStack.Extract;
      BufferStack.TrimExcess;
      TV.Items.Delete(PStandNode.FTreeNode);
      PStandNode.FTreeNode := nil;
      PStandNode.FLinks := nil;
      PStandNode.FRechts := nil;
      FreeAndNil(PStandNode);
    end;
    BufferStack.Clear;
    BufferStack.Free;
  end;
  if rl = 'r' then
  begin
    if PStandNode.FRechts <> nil then
    begin
      PStandBufferNode.FRechts.FTreeNode.MoveTo(PParentNode.FTreeNode, naAddChildFirst);   //Nicht löschen, sondern so wie unten
    end;
    TV.Items.Delete(PParentNode.FRechts.FTreeNode);
    PParentNode.FRechts := PStandBufferNode.FRechts;
  end
  else if rl = 'l' then
  begin
    if PStandBufferNode.FLinks <> nil then
    begin
      PStandBufferNode.FLinks.FTreeNode.MoveTo(PParentNode.FTreeNode, naAddChild);
    end;
    TV.Items.Delete(PParentNode.FLinks.FTreeNode);
    PParentNode.FLinks := PStandBufferNode.FLinks;
  end
  else
  begin
    ShowMessage(' (rl <> r) and (rl <> l)');
  end;
  while BufferTextStack.Count <> 0 do
  begin
    Einfuegen(BufferTextStack.Peek);
    BufferTextStack.Extract;
    BufferTextStack.TrimExcess;
  end;
  if BufferTextStack <> nil then
  begin
    BufferTextStack.Clear;
    BufferTextStack.Free;
  end;
  FreeAndNil(TStandBufferNode);
  PStandNode := PWurzelNode;
  PStandNode.FTreeNode.Selected := True;
  Lb_Ausgabe.Caption := PStandNode.FDaten;
  StatusBt;
end;

procedure TForm4.Bt_NodeZaehlenClick(Sender: TObject);
var
  Stack: TStack<PNode>;
  PBufferNode: PNode;
  i: Integer;
begin
  if PWurzelNode <> nil then
  begin
    Stack := TStack<PNode>.Create;
    i := 0;
    PBufferNode := PWurzelNode;
    Inc(i);
    if ((PWurzelNode.FLinks <> nil) and (PWurzelNode.FRechts <> nil)) then
    begin
      Stack.Push(PBufferNode);
      PBufferNode := PBufferNode.FLinks;
      Inc(i);
    end;
    if Stack.Count <> 0 then
    begin
      repeat
      begin
        if ((PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil)) then
        begin
          if (Stack.Count = 0) or (Stack.Peek <> PBufferNode) then
          begin
            Stack.Push(PBufferNode);
          end;
          PBufferNode := PBufferNode.FLinks;
        end
        else if PBufferNode.FRechts <> nil then
        begin
          PBufferNode := PBufferNode.FRechts;
        end
        else if PBufferNode.FLinks <> nil then
        begin
          PBufferNode := PBufferNode.FLinks;
        end
        else
        begin
          PBufferNode := Stack.Peek;
          Stack.Extract;
          Stack.TrimExcess;
          PBufferNode := PBufferNode.FRechts;
          if (PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil) then
          begin
            Stack.Push(PBufferNode);
          end;
        end;
        Inc(i);
      end;
      until Stack.Count = 0;
    end;
    Stack.Clear;
    Stack.Free;
    ShowMessage('Es gibt ' + IntToStr(i) + ' Knoten');
  end
  else
  begin
    ShowMessage('Es gibt 0 Knoten');
  end;
end;

procedure TForm4.Bt_RechtsClick(Sender: TObject);
begin
  PStandNode.FTreeNode.Selected := False;
  PParentNode := PStandNode;
  PStandNode := PStandNode.FRechts;
  PStandNode.FTreeNode.Selected := True;
  Lb_Ausgabe.Caption := PStandNode.FDaten;
  StatusBt;
end;

procedure TForm4.Bt_TiefeClick(Sender: TObject);
begin
  ShowMessage('Tiefe: ' + IntToStr(Hoehe(PWurzelNode)));
end;

procedure TForm4.Bt_WurzelClick(Sender: TObject);
begin
  PStandNode.FTreeNode.Selected := False;
  PStandNode := PWurzelNode;
  Lb_Ausgabe.Caption := PStandNode.FDaten;
  StatusBt;
  PParentNode := nil;
  PStandNode.FTreeNode.Selected := True;
end;

procedure TForm4.FormCreate(Sender: TObject);
begin
  Bt_Links.Enabled := False;
  Bt_Rechts.Enabled := False;
  Bt_Wurzel.Enabled := False;
  Bt_Aendern.Enabled := False;
  PWurzelNode := nil;
  PStandNode := nil;
  PParentNode := nil;
  Tag := 0;
  //AUF 42 ZEICHEN BESCHRÄNKEN
  Ed_Eingabe.MaxLength := 42;
  TV.HideSelection := False;
  TV.FullExpand;
end;

procedure TForm4.StatusBt;
begin
  Bt_Links.Enabled := PStandNode.FLinks <> nil;
  Bt_Rechts.Enabled := PStandNode.FRechts <> nil;
  Bt_Aendern.Enabled := PWurzelNode <> nil;
end;

procedure TForm4.TVMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if (TV.Selected <> nil) and (TV.Selected <> PStandNode.FTreeNode) then
  begin
    AktuallisiereMaus; //Nach PNode suchen, welches PNode.TreeNode = TV.Selected hat und PStandNode := PNode(Buffer) und Anzeige, Buttons,... aktuallisieren
  end;
end;

procedure TForm4.AktuallisiereMaus;
var
  Stack: TStack<PNode>;
begin
  if PWurzelNode <> nil then
  begin
    PStandNode.FTreeNode.Selected := False;
    PParentNode := nil;
    Stack := TStack<PNode>.Create;
    PStandNode := PWurzelNode;
    if ((PStandNode.Flinks <> nil) and (PStandNode.FRechts <> nil)) and (PStandNode.FTreeNode <> TV.Selected) then
    begin
      Stack.Push(PStandNode);
      PParentNode := PStandNode;
      PStandNode := PStandNode.FLinks;
    end;
    if PStandNode.FTreeNode <> TV.Selected then
    begin
      repeat
      begin
        if ((PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil)) and (PStandNode.FTreeNode <> TV.Selected) then
        begin
          if (Stack.Count = 0) or (Stack.Peek <> PStandNode) then
          begin
            Stack.Push(PStandNode);
          end;
          PParentNode := PStandNode;
          PStandNode := PStandNode.FLinks;
        end
        else if PStandNode.FRechts <> nil then
        begin
          PParentNode := PStandNode;
          PStandNode := PStandNode.FRechts;
        end
        else if PStandNode.FLinks <> nil then
        begin
          PParentNode := PStandNode;
          PStandNode := PStandNode.FLinks;
        end
        else
        begin
          PStandNode := Stack.Peek;
          Stack.Extract;
          Stack.TrimExcess;
          PParentNode := PStandNode;
          PStandNode := PStandNode.FRechts;
          if (PStandNode.FLinks <> nil) and (PStandNode.FRechts <> nil) then
          begin
            Stack.Push(PStandNode);
          end;
        end;
      end;
      until PStandNode.FTreeNode = TV.Selected;
    end;
      Stack.Clear;
      Stack.Free;
      PStandNode.FTreeNode.Selected := True;
      Lb_Ausgabe.Caption := PStandNode.FDaten;
      StatusBt;
  end;
end;

function TForm4.Hoehe;
var
  links, rechts: Integer;
begin
  if p = nil then
  begin
    result := 0;
  end
  else
  begin
    links := Hoehe(p.FLinks) + 1 ;
    rechts := Hoehe(p.FRechts) + 1;
    if rechts > links then
    begin
      result := rechts;
    end
    else
    begin
      result := links;
    end;
  end;
end;

function TForm4.GetErgebnis;
var
  ergebnis: TStringList;
  Stack: TStack<PNode>;
  PBufferNode: PNode;
begin
  ergebnis := TStringList.Create;
  if PWurzelNode <> nil then
  begin
    eingegeben := True;
    Stack := TStack<PNode>.Create;
    ergebnis := TStringList.Create;
    PBufferNode := PWurzelNode;
    ergebnis.Add(PBufferNode.FDaten);
    if (PWurzelNode.FLinks <> nil) and (PWurzelNode.FRechts <> nil) then
    begin
      Stack.Push(PBufferNode);
      PBufferNode := PBufferNode.FLinks;
      ergebnis.Add(PBufferNode.FDaten);
    end;
    if Stack.Count <> 0 then
    begin
      repeat
      begin
        if ((PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil)) then
        begin
          if Stack.Peek <> PBufferNode then
          begin
            Stack.Push(PBufferNode);
          end;
          PBufferNode := PBufferNode.FLinks;
        end
        else if PBufferNode.FRechts <> nil then
        begin
          PBufferNode := PBufferNode.FRechts;
        end
        else if PBufferNode.FLinks <> nil then
        begin
          PBufferNode := PBufferNode.FLinks;
        end
        else
        begin
          PBufferNode := Stack.Peek;
          Stack.Extract;
          Stack.TrimExcess;
          PBufferNode := PBufferNode.FRechts;
          if (PBufferNode.FLinks <> nil) and (PBufferNode.FRechts <> nil) then
          begin
            Stack.Push(PBufferNode);
          end;
        end;
        ergebnis.Add(PBufferNode.FDaten);
      end;
      until Stack.Count = 0;
    end;
      Stack.Clear;
      Stack.Free;
    end
    else
    begin
      eingegeben := False;
    end;
    result := ergebnis;
end;

function TForm4.Durchgelaufen;
begin
  result := eingegeben;
end;

procedure TForm4.SetErgebnis;
var
  i: Integer;
begin
  i := 0;
  while i < daten.Count do
  begin
    Einfuegen(daten[i]);
    Inc(i);
  end;
end;
end.