Imports System
Imports System.Collections.Generic
' Sudoku solution must satisfy all of the following rules:
' Each of the digits 1-9 must occur once in each row.
' Each of the digits 1-9 must occur once in each column.
' Each of the digits 1-9 must occur once in each 3x3 grid.
Class SudokuValidator
Public Shared Function IsValidSudoku3x3Grid(ByVal grid As Integer(,)) As Boolean
Dim rows As Integer = grid.GetLength(0)
Dim cols As Integer = grid.GetLength(1)
If rows <> 3 OrElse cols <> 3 Then Return False
Dim seen As HashSet(Of Integer) = New HashSet(Of Integer)()
For i As Integer = 0 To rows - 1
For j As Integer = 0 To cols - 1
Dim num As Integer = grid(i, j)
If num < 1 OrElse num > 9 OrElse seen.Contains(num) Then Return False
seen.Add(num)
Next
Next
Return True
End Function
Public Shared Sub Main()
Dim grid As Integer(,) = {
{5, 3, 4},
{6, 7, 2},
{1, 9, 8}}
If IsValidSudoku3x3Grid(grid) Then
Console.WriteLine("The grid is a valid Sudoku grid!")
Else
Console.WriteLine("The grid is NOT a valid Sudoku grid!")
End If
End Sub
End Class
' run
'
' The grid is a valid Sudoku grid!
'
