1. (2023高一下·香格里拉月考) 對一個n×n的矩陣以“行”為單位進(jìn)行升序排序，如下表所示是一個4×4的矩陣以行為單位進(jìn)行升序排序。

李華編寫了實現(xiàn)上述功能的程序，程序功能如下：程序運行時，在文本框Text1中輸入n（1<=n<=10）單擊“產(chǎn)生”按鈕Command1產(chǎn)生n×n個隨機(jī)數(shù)，隨機(jī)數(shù)的范圍為[0,9],隨機(jī)存儲在數(shù)組a中，并以矩陣的形式在列表框List1上顯示。單擊“排序”按鈕Command2，對矩陣以“行”為單位進(jìn)行升序排序，并在列表框List2輸出排序后的矩陣。在程序運行界面如下圖所示。

實現(xiàn)上述功能的VB程序如下，請在劃線處填入合適的代碼。

Dim n As Integer

Dim a(1 To 100) As Integer

Private Sub Command1_Click( )

    Dim i As Integer, s As String

    s = ""

   

    For i = 1 To n * n

        

        s = s + Str(a(i))

        If i Mod n = 0 Then

            List1.AddItem s

            s = ""

        End If

    Next i

End Sub

Private Sub Command2_Click()

    Dim i As Integer, j As Integer, t As Integer

    Dim s As String

    s = ""

    For i = 1 To n * n

        k = i

        For j = i + 1 To

            If a(j) < a(k) Then k = j

        Next j

        If k <> i Then t = a(k):a(k) = a(i):a(i) = t

       

        If i Mod n = 0 Then

            List2.AddItem s

            s = ""

        End If

    Next i

End Sub