第７話 ３以外の３の倍数も探索対象から外すと？
前話解答例
Dim cn As Long
Dim s(10000000) As Long
Private Sub CommandButton1_Click()
Call CommandButton2_Click
Dim i As Long, a As Long, cns As Long
Dim hj As Single, ow As Single
hj = Timer
s(0) = 2
cn = 1
Cells(6, 1) = 2
For i = 3 To 10000000 Step 2
If i Mod 3 = 0 Then
i = i + 2
If i > 10000000 Then Exit For
End If
If sh(i) = 1 Then
a = cn Mod 200
cns = Int(cn / 200)
Cells(6 + cns, 1 + a) = i
s(cn) = i
cn = cn + 1
End If
Next
ow = Timer
Cells(4, 1) = "素数生成にかかった時間は"
Cells(4, 5) = ow - hj
Cells(4, 6) = "秒です。"
Cells(5, 1) = "生成された素数は"
Cells(5, 4) = cn
Cells(5, 5) = "個です。"
End Sub
Function sh(a As Long)
If a = 1 Then
sh = 0
Exit Function
End If
If a = 2 Then
sh = 1
Exit Function
End If
If a Mod 2 = 0 Then
sh = 0
Exit Function
End If
Dim q As Long, i As Long
q = Int(Sqr(a))
For i = 0 To cn
If s(i) > q Then
sh = 1
Exit Function
End If
If a Mod s(i) = 0 Then
sh = 0
Exit Function
End If
Next
sh = 1
End Function
Private Sub CommandButton2_Click()
Range("4:50000").Select
Selection.ClearContents
Cells(1, 1).Select
End Sub
実行例
参考ダウンロード添付ファイル
すべて探索する場合
