unit1.~pas

对数据的递归折半查找 效率较高,能在短时间内找到所要求的内容

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Memo1: TMemo;
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  mid:integer;

implementation

{$R *.DFM}

CONST
  N=100;
TYPE
  colarr=ARRAY[1..N] OF INTEGER;
VAR
  a:colarr;

procedure ReadArray(var a:colarr;var m:INTEGER);
var
  line:String;
  k:INTEGER;
begin
  m:=0;
  line:=trim(Form1.Memo1.Lines[0]);
  line:=line+' ';
  while (not (line='')) and (m<N) DO
    Begin
      m:=m+1;
      k:=Pos(' ',line);
      a[m]:=StrToInt(Copy(line,1,k-1));
      line:=TrimLeft(Copy(line,k+1,Length(line)-k));
    End;
end;

function z(top,bot,x:integer):integer;
var c:integer;
begin
  mid:=(top+bot) DIV 2;
  if (bot>=top) then
    begin
    IF (x=a[mid]) THEN c:=1
    ELSE
    begin
      IF (x<a[mid]) THEN c:=z(1,mid-1,x)
      ELSE c:=z(mid+1,bot,x);
    end;
    end
  else
  c:=0;
  result:=c;
end;

procedure TForm1.Button1Click(Sender: TObject);
VAR
  x,m,asd,top,bot:INTEGER;
BEGIN
  x:=strtoint(Edit1.Text);
  ReadArray(a,m);
  asd:=z(1,m,x);
  IF (asd=0) THEN ShowMessage('没有找到！')
  ELSE ShowMessage('找到'+IntToStr(x)+', 位置为：'+IntToStr(mid));
END;

end.