Question

利用vb编写一道数列题

s=1*2-2*3+3*4-4*5+……+(-1)^(n-1)*n*(n+1)
还有一题：
用随机函数产生20个区间位于[1, 100]的随机整数，分别计算其中所含奇数与偶数的平均值。

Answer 1

1.Private Sub Form_click()
Dim m, n, sum
sum = 0
m = Val(InputBox("请输入一个数以求和"))
Do
sum = sum + (-1) ^ (n - 1) * n * (n + 1)
n = n + 1
Loop Until n > m
Print sum
End Sub

2. Private Sub Form_click()
Dim a(19)
Dim m(), n() 'm()为偶数集, n()为奇数集
Dim i, p, q
Dim sum
Dim avg1, avg2 'avg1为奇数平均数, avg2为偶数平均数

For i = 0 To 19
Randomize
a(i) = Int(Rnd() * 99 + 1)
If a(i) Mod 2 = 0 Then '判断偶数，是，将存入偶数集
p = p + 1
ReDim Preserve m(p)
m(p) = a(i)

Else '不是，将存入奇数集
q = q + 1
ReDim Preserve n(q)
n(q) = a(i)

End If
Next i

For p = LBound(m()) To UBound(m())
sum = sum + m(p)
Next p
Print sum
avg2 = sum / UBound(m())
Print "20个数中偶数之平均数为" & avg2

sum = 0
For q = LBound(n()) To UBound(n())
sum = sum + n(q)
Next q
Print sum
avg1 = sum / UBound(n())
Print "20个数中奇数之平均数为" & avg1

End Sub