对分查找.frm

算法教案

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "对分查找"
   ClientHeight    =   3945
   ClientLeft      =   60
   ClientTop       =   450
   ClientWidth     =   4335
   LinkTopic       =   "Form1"
   ScaleHeight     =   3945
   ScaleWidth      =   4335
   StartUpPosition =   3  '窗口缺省
   Begin VB.CommandButton Command1 
      Caption         =   "查找"
      Height          =   375
      Left            =   2760
      TabIndex        =   8
      Top             =   3360
      Width           =   975
   End
   Begin VB.TextBox Text3 
      BackColor       =   &H00FF0000&
      Height          =   375
      Left            =   2640
      Locked          =   -1  'True
      TabIndex        =   7
      Top             =   2640
      Width           =   1335
   End
   Begin VB.TextBox Text2 
      BackColor       =   &H00FF0000&
      Height          =   375
      Left            =   2640
      Locked          =   -1  'True
      TabIndex        =   5
      Top             =   1440
      Width           =   1335
   End
   Begin VB.TextBox Text1 
      BackColor       =   &H0000FFFF&
      Height          =   375
      Left            =   2640
      TabIndex        =   3
      Top             =   480
      Width           =   1335
   End
   Begin VB.ListBox List1 
      BackColor       =   &H00FF0000&
      Height          =   3300
      ItemData        =   "对分查找.frx":0000
      Left            =   120
      List            =   "对分查找.frx":0002
      TabIndex        =   0
      Top             =   480
      Width           =   2175
   End
   Begin VB.Label Label4 
      Caption         =   "查找的次数"
      Height          =   375
      Left            =   2640
      TabIndex        =   6
      Top             =   2040
      Width           =   1335
   End
   Begin VB.Label Label3 
      Caption         =   "查找的结果"
      Height          =   255
      Left            =   2640
      TabIndex        =   4
      Top             =   960
      Width           =   1095
   End
   Begin VB.Label Label2 
      Caption         =   "输入查找键"
      Height          =   255
      Left            =   2640
      TabIndex        =   2
      Top             =   120
      Width           =   1215
   End
   Begin VB.Label Label1 
      Caption         =   "数组d中的数据"
      Height          =   255
      Left            =   240
      TabIndex        =   1
      Top             =   120
      Width           =   1215
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Dim d(1 To 128) As Integer
Dim nc As Integer
Function adj(a As String, n As Integer) As String
    Dim sa As String
    sa = a: na = Len(a)
    For i = 1 To n - na
        sa = " " + sa
    Next i
    adj = sa
End Function
Function search(key As Integer) As Integer     '对分查找算法
    Dim pos, i, j  As Integer
    i = 1: j = 128: nc = 0
    Do While i <= j
       nc = nc + 1
       m = Fix((i + j) / 2)
       If d(m) = key Then
        search = m: Exit Function             '找到，返回在数组中的序号
       End If
       If key < d(m) Then
          j = m - 1
       Else
          i = m + 1
       End If
    Loop
    search = 0                               '返回结果,0表示未找到
End Function

Private Sub Command1_Click()
    Dim k, pos As Integer
    pos = search(Val(Text1.Text))            '进行查找
    If pos = 0 Then Text2.Text = "找不到" Else Text2.Text = "在d(" + Str(pos) + ")中"
    Text3.Text = nc
    nc = 0
End Sub

Private Sub Form_Load()
    Dim dv As Integer
    dv = 2
    For i = 1 To 128
        dv = dv + Fix((Timer() Mod 67 + 13) * Rnd) + 1  '随机产生递增序列的整数
        d(i) = dv
        List1.AddItem adj(Str(i), 3) + ":" + adj(Str(d(i)), 6)
    Next i
End Sub

Private Sub Text1_Click()
   Text1.Text = ""
   Text2.Text = ""
   Text3.Text = ""
End Sub