Randomize Timer

Sub printSquare(latin() As Integer, n As Integer)
    For i As Integer = 0 To n - 1
        Print "[";
        For j As Integer = 0 To n - 1
            Print latin(i, j); ",";
        Next j
        Print Chr(8); " ]"
    Next i
    Print
End Sub

Sub latinSquare(n As Integer)
    Dim As Integer i, j, k

    If n <= 0 Then
        Print "[]"
        Exit Sub
    End If
    Dim latin(n - 1, n - 1) As Integer
    For i = 0 To n - 1
        For j = 0 To n - 1
            latin(i, j) = j
        Next j
    Next i

    ' first row
    For i = 0 To n - 1
        Dim j As Integer = Int(Rnd * n)
        Swap latin(0, i), latin(0, j)
    Next i

    ' middle row(s)
    For i = 1 To n - 2
        Dim shuffled As Integer = 0
        While shuffled = 0
            For j = 0 To n - 1
                Dim k As Integer = Int(Rnd * n)
                Swap latin(i, j), latin(i, k)
            Next j
            shuffled = 1
            For k As Integer = 0 To i - 1
                For j = 0 To n - 1
                    If latin(k, j) = latin(i, j) Then
                        shuffled = 0
                        Exit For
                    End If
                Next j
                If shuffled = 0 Then Exit For
            Next k
        Wend
    Next i

    ' last row
    For j = 0 To n - 1
        Dim used(n - 1) As Integer
        For i = 0 To n - 2
            used(latin(i, j)) = 1
        Next i
        For k = 0 To n - 1
            If used(k) = 0 Then
                latin(n - 1, j) = k
                Exit For
            End If
        Next k
    Next j
    printSquare(latin(), n)
End Sub

latinSquare(5)
latinSquare(5)
latinSquare(10) ' for good measure

Sleep