氣泡排序詳解

下面程式從比大小、交換、三個數排序、四個數排序、N個數排序，循序詳細解說氣泡排序的構成，讀者可利用「F8」逐步執行，了解每個指令的執行情形。



1 Public Class Form1
2 
3     Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
4 
5         Dim a, b, c, t As Integer
6         a = 20
7         b = 10
8 
9         '比大小
10         If a > b Then Debug.Print(a & ">" & b)
11         If a < b Then Debug.Print(a & "<" & b)
12         If a = b Then Debug.Print(a & "=" & b)
13 
14         '交換
15         Debug.Print(a & "," & b)
16         t = a
17         a = b
18         b = t
19         Debug.Print(a & "," & b)
20 
21         '由小至大
22         a = 10
23         b = 20
24         Debug.Print(a & "," & b)
25         If a > b Then
26             t = a
27             a = b
28             b = t
29         End If
30         Debug.Print(a & "," & b)
31 
32         '由小至大--三個數
33         a = 20
34         b = 30
35         c = 15
36         Debug.Print(a & "," & b & "," & c)
37         For i = 1 To 2
38             If a > b Then
39                 t = a
40                 a = b
41                 b = t
42             End If
43             If b > c Then
44                 t = b
45                 b = c
46                 c = t
47             End If
48         Next i
49         Debug.Print(a & "," & b & "," & c)
50 
51         '由小至大--四個數
52         Dim z(5) As Integer
53         z(1) = 20
54         z(2) = 30
55         z(3) = 15
56         z(4) = 5
57         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4))
58         For i = 1 To 3
59             If z(1) > z(2) Then
60                 t = z(1)
61                 z(1) = z(2)
62                 z(2) = t
63             End If
64             If z(2) > z(3) Then
65                 t = z(2)
66                 z(2) = z(3)
67                 z(3) = t
68             End If
69             If z(3) > z(4) Then
70                 t = z(3)
71                 z(3) = z(4)
72                 z(4) = t
73             End If
74         Next i
75         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4))
76 
77         '由小至大--四個數--重覆動作改寫為迴路
78         ' Dim z(5) As Integer
79         z(1) = 20
80         z(2) = 30
81         z(3) = 15
82         z(4) = 5
83         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4))
84         For i = 1 To 3
85             For j As Integer = 1 To 3
86                 If z(j) > z(j + 1) Then
87                     t = z(j)
88                     z(j) = z(j + 1)
89                     z(j + 1) = t
90                 End If
91             Next j
92         Next i
93         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4))
94 
95         '由小至大--四個數--重覆動作改寫為迴路--改寫為N筆適用--輸出至MsgBox
96         ' Dim z(5) As Integer
97         Dim n As Integer = 5
98         z(1) = 20
99         z(2) = 30
100         z(3) = 15
101         z(4) = 5
102         z(5) = 10
103         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4) & "," & z(5))
104         For i = 1 To n - 1
105             For j As Integer = 1 To n - 1
106                 If z(j) > z(j + 1) Then
107                     t = z(j)
108                     z(j) = z(j + 1)
109                     z(j + 1) = t
110                 End If
111             Next j
112         Next i
113         Debug.Print(z(1) & "," & z(2) & "," & z(3) & "," & z(4) & "," & z(5))
114         Dim msgStr As String = ""
115         For i = 1 To n
116             msgStr = msgStr & z(i) & " "
117         Next
118         MsgBox(msgStr)
119     End Sub
120 End Class