回溯算法_解数独1

Private Function solveSudokuHelper(board) As Boolean
    For i = 0 To 8
        For j = 0 To 8
            If (board(i, j) = ".") Then
                For k = 1 To 9
                    If isValidSudoku(i, j, k, board) Then
                        board(i, j) = k
                        If solveSudokuHelper(board) Then solveSudokuHelper = True: Exit Function
                        board(i, j) = "."
                    End If
                Next
                solveSudokuHelper = False: Exit Function
            End If
        Next
    Next
    solveSudokuHelper = True
End Function

Sub h21_回溯算法_解数独1() '数组起始下标为0
    tms = Timer '程序起始时间
    With Sheet1
        .Range("m1").CurrentRegion.ClearContents
        ar = .Range("a1").CurrentRegion
        Dim board(0 To 8, 0 To 8)
        For x = 1 To UBound(ar)
            For y = 1 To UBound(ar, 2)
                board(x - 1, y - 1) = ar(x, y)
            Next
        Next
        res = solveSudokuHelper(board)
        .Range("m1").Resize(UBound(board) + 1, UBound(board, 2) + 1) = board
    End With
    MsgBox Format(Timer - tms, "0.0s ") & s
End Sub

Private Function isValidSudoku(row, col, Val, board) As Boolean
    For i = 0 To 8
        If board(row, i) = Val Then isValidSudoku = False: Exit Function
    Next
    For j = 0 To 8
        If board(j, col) = Val Then isValidSudoku = False: Exit Function
    Next
    startrow = (VBA.Int(row / 3)) * 3
    startcol = (VBA.Int(col / 3)) * 3
    For i = startrow To startrow + 2
        For j = startcol To startcol + 2
            If board(i, j) = Val Then isValidSudoku = False: Exit Function
        Next
    Next
    isValidSudoku = True
End Function