slBTR

Unit Unit2;

Interface

Uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

Type
  TFormAddElement = class(TForm)
    Label1: TLabel;
    EditAdd: TEdit;
    ButtonOK: TButton;
    Procedure ButtonOKClick(Sender: TObject);
    Procedure FormClose(Sender: TObject; var Action: TCloseAction);
  Private
  Public
  end;

Type
  SinglyLinkedList = class
  Type PNode = ^TNode;   { указатель на узел }
    TNode = record    { структура узла }
       Element: Integer; { элемент }
       Index: Word;    { индекс узла }
       NextNode: PNode;      { ссылка на следующий }
     End;
  Private
      FHeaderNode: PNode;
      FLastNode: PNode;
      Function IsEmpty: Boolean;
      Function GetSize: Word;
      Function NodeDataWithIndex(AIndex: Word): TNode;
  Public
      Constructor Create;
      Destructor Destroy;
      Procedure Append(ANodeElement: Integer);
      Procedure ShowCountElementEnter(Element: Word);
      Procedure Clear;
      Function PopLast: Integer;
      Procedure Remove(AIndex: Word);
      Procedure Debug;
  End;

Var
    FormAddElement: TFormAddElement;
    List: SinglyLinkedList;
    IsDeleteble: Boolean = False;
    IsAdd: Boolean = False;
    IsEnter: Boolean = False;
    Count: Integer = 1;

Implementation
Uses Unit1;

Procedure SinglyLinkedList.Debug();
Var
    CurNode: PNode;
Begin
    CurNode := FHeaderNode^.NextNode;
    While CurNode <> Nil do
    Begin
        ShowMessage(IntToStr(CurNode^.Element));
        CurNode := CurNode^.NextNode;
    End;
End;

Function SinglyLinkedList.IsEmpty: Boolean;
Begin
    if FHeaderNode^.NextNode = Nil then
        IsEmpty := True
    else
        IsEmpty := False;
End;

Procedure SinglyLinkedList.ShowCountElementEnter(Element: Word);
Var
    Count, I: Word;
Begin
    Count := 0;
    I := 0;
    While I < GetSize do
    Begin
        if (Element = NodeDataWithIndex(I).NextNode.Element) then
            Inc(Count);
        Inc(I);
    End;
    ShowMessage('Количество вхождений элемента ' + IntToStr(Element) + ' в список = '+ IntToStr(Count));
End;

Function SinglyLinkedList.GetSize: Word;
Var
    CurrentNode: TNode;
Begin
    If IsEmpty then
        GetSize := 0
    Else
    Begin
        CurrentNode.NextNode := FHeaderNode^.NextNode;
        CurrentNode.Index := 0;
        While CurrentNode.NextNode <> Nil do
        Begin
            CurrentNode.NextNode := CurrentNode.NextNode^.NextNode;
            Inc(currentNode.Index);
        End;
        GetSize := CurrentNode.Index;
    End;
End;

Constructor SinglyLinkedList.Create();
Begin
    New(FHeaderNode);
    FHeaderNode^.NextNode := Nil;
    FLastNode := FHeaderNode;
End;

Destructor SinglyLinkedList.Destroy;
Begin
    Clear;
    Dispose(FHeaderNode);
End;

Function SinglyLinkedList.NodeDataWithIndex(AIndex: Word): TNode;
Var
    CurrentData: TNode;
Begin
    CurrentData.NextNode := FHeaderNode^.NextNode;
    CurrentData.Index := 0;
    While CurrentData.Index <> AIndex do
    Begin
        CurrentData.NextNode := CurrentData.NextNode^.NextNode;
        Inc(CurrentData.Index);
    End;
    NodeDataWithIndex := CurrentData;
End;

Procedure SinglyLinkedList.Append(ANodeElement: Integer);
Var
    CurrentNode: PNode;
Begin
    CurrentNode := FLastNode;
    New(CurrentNode^.NextNode);
    CurrentNode := CurrentNode^.NextNode;
    CurrentNode^.Element := ANodeElement;
    CurrentNode^.NextNode := Nil;
    FLastNode := CurrentNode;
End;

Procedure SinglyLinkedList.Clear;
Begin
    While FHeaderNode^.NextNode <> Nil do
        PopLast;
End;

Function SinglyLinkedList.PopLast: Integer;
Var
    I: Word;
    CurrentNode: PNode;
Begin
    If FHeaderNode^.NextNode <> Nil then
    Begin
        CurrentNode := FHeaderNode;
        While CurrentNode^.NextNode <> FLastNode do
            CurrentNode := CurrentNode^.NextNode;

        PopLast := FLastNode^.Element;

        Dispose(CurrentNode^.NextNode);
        FLastNode := CurrentNode;
        FLastNode^.NextNode := Nil;
    End;
End;

Procedure SinglyLinkedList.Remove(AIndex: Word);
Var
    CurrentData: TNode;
    BuffLastNode: PNode;
Begin
    If AIndex = 0 then
    Begin
        CurrentData.NextNode := FHeaderNode;
        CurrentData.Index := 0;
    End
    Else
        CurrentData := NodeDataWithIndex(AIndex - 1);
    If AIndex = GetSize-1 then
        PopLast
    Else
    Begin
        BuffLastNode := FLastNode;
        FLastNode := CurrentData.NextNode^.NextNode;
        CurrentData.NextNode^.NextNode := FLastNode^.NextNode;
        FLastNode := BuffLastNode;
    End;
End;

{$R *.dfm}

Function IsElementCorrect(EditAdd:TEdit):Boolean;
Var
    IsCorrect: Boolean;
Begin
    IsCorrect := True;
    Try
        StrToInt(EditAdd.Text)
    Except
        IsCorrect := False;
    End;
    IsElementCorrect := IsCorrect;
End;


Procedure TFormAddElement.ButtonOKClick(Sender: TObject);
Var
    Element: Integer;
Begin
    If IsAdd then
    Begin
        If count = 1 then
        Begin
            List := SinglyLinkedList.Create();
            IsDeleteble := True;
        End;
        If IsElementCorrect(EditAdd) then
        Begin
            Element := StrToInt(EditAdd.Text);
            ListForm.StringGrid1.Cells[1,count] := EditAdd.Text;
            ListForm.StringGrid1.Cells[0,count] := IntToStr(Count);
            ListForm.StringGrid1.RowCount := ListForm.StringGrid1.RowCount + 1;
            List.Append(Element);
            Inc(Count);
            EditAdd.Text := '';
            IsAdd := False;
            FormAddElement.Close;
        End
        Else
            MessageDlg('Введите целое число в пределах +- 2*10^9!', mtError, [mbOK], 0)
    End;
    If IsEnter then
    Begin
        If IsElementCorrect(EditAdd) then
        Begin
            Element := StrToInt(EditAdd.Text);
            List.ShowCountElementEnter(Element);
            //ShowMessage(IntToStr(List.ShowCountElementEnter(Element)));
            IsEnter := False;
            FormAddElement.Close;
        End;
    End;
End;

Procedure TFormAddElement.FormClose(Sender: TObject; var Action: TCloseAction);
Begin
    IsEnter := False;
    IsAdd := False;
    EditAdd.Text := '';
End;

End.