VB代码：

(2018年4月浙江)17．分析数组a中各元素依次变化的情况，进行如下定义： ●变化段：数组中相邻两个元素构成一个变化段。变化段有上升段(a(i)>a(i-1))、下降段(a(i)

●波峰：从上升段到下降段形成一个波峰。波峰的起点是峰顶前所有连续上升段中的第1个，终点是峰顶后所有连续下降段中的最后1个。

●对称波峰：上升段与下降段个数相同的波峰称为对称波峰。

下图为一组数据的变化段及波峰示意图。

现要求统计数组a各元素依次变化过程中“对称波峰”的个数。小李依据上述描述设计了如下VB程序。请回答下列问题： (1)数组元素“1，4，3，3，2，6，8，7，9，3，4，7，9，6，3，1”依次变化过程中“对称波峰”的个数为。 (2)请在划线处填入合适的代码。 Const n = 16 Dim a(1 To n) As Integer Private Sub Command1_Click() Dim flag As Integer, count As Integer, steps As Integer, i As Integer flag = 0: steps = 0: count = 0 For i =① To n

If a(i) > a(i – 1) Then

If issympeak(flag, steps) Then count = count + 1

If flag = 0 Or flag = -1 Then

②

Else

steps = steps + 1

End If

flag = 1

ElseIf a(i) = a(i – 1) Then

If issympeak(flag, steps) Then count = count + 1

steps = 0

flag = 0

Else

steps = steps – 1

flag = -1

End If Next i If issympeak(flag, steps) Then count = count + 1

Text1.Text = Str(count) End Sub Function issympeak(flag As Integer, steps As Integer) As Boolean

If③ Then issympeak = True Else issympeak = False End Function Private Sub FormLoad() ‘读取数据，并存储到数组a中。代码略 End Sub参考答案：(1)3 (2) ①2 ②steps = 1 ③flag = -1 And steps = 0 或其他等价表达式

def issympeak(flag,steps):

if flag==-1 and steps==0:

return True

return False a=[1,4,3,3,2,6,8,7,9,3,4,7,9,6,3,1] n=len(a) print(a) flag=0 steps=0 count=0 for i in range(1,n):

if a[i]>a[i-1]:

if issympeak(flag,steps):

count=count+1

if flag==0 or flag==-1:

steps=1

else:

steps=steps+1

flag=1

elif a[i]==a[i-1]:

if issympeak(flag,steps):

count=count+1

steps=0

flage=0

else:

steps=steps-1

flag=-1 if issympeak(flag,steps):

count=count+1 print(‘对称波峰的个数为：’,count)

出处：/articlelist/uploads/allimg/220410/2115415011-0.jpg