umain.~pas

数据结构二分查找

unit uMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, ADODB;

const
  MaxLen =100;
type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Memo1: TMemo;
    Button2: TButton;
    Memo2: TMemo;
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    FList:array[0..MaxLen] of Integer;
    function Search(Key:integer):Integer;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  i,j:integer;
begin
  //生成随机数组
  Randomize;
  j:=0;
  for i := 0 to MaxLen do
  begin
    j:=j+random(3)+1;
    FList[i]:=j;
    Memo2.Lines.Add(Format('%d : %d',[i,j]));
  end;//End For
  Memo2.Lines.Add(Format('%d : %d',[i,j]));
end;

function TForm1.Search(Key:integer):Integer;
var
  Curpos,LowPos,HighPos ,count,n:integer;
begin
  Result :=-1;
  LowPos := Low(FList) ;
  HighPos := High(FList);
  n := HighPos - LowPos -1;
  count := 0;
  while FList[LowPos] <= FList[HighPos] do
  begin
    Inc(count);
    //Curpos := LowPos + Trunc((Key - Flist[LowPos])/(FList[HighPos]-FList[LowPos])*n);
    Curpos := (HighPos + LowPos ) div 2 ;
    if FList[Curpos] = key then
    begin
      Result := Curpos;
      Break;
    end;
    if Key>FList[Curpos] then
      LowPos := Curpos + 1
    else
      HighPos := Curpos -1;
  end;//End While
  Memo1.Lines.Add('查找次数:'+IntToStr(count)); //调试
end;                

procedure TForm1.Button1Click(Sender: TObject);
var
  Curpos,Key:integer;
begin
  Button2.Enabled := True;
  Key := StrToInt(Edit1.Text);

  Curpos :=  Search(key);

  if Curpos>=0 then
  begin
    Memo1.Lines.Add(Format('查找 %d 成功;位置 %d FList[pos] = %d '
    ,[Key,Curpos,FList[Curpos]]));
  end
  else
  begin
    Memo1.Lines.Add(Format('查找 %d 失败 ',[Key ])) ;
  end
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Button2.Enabled := False;
end;

end.