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Beginner’s Guide to Code Algorithms

50

STEP 11 continued

Once identified, we store the two digits as a string in an array we call

putnumberpresent.

  If sbox(i, j) =​ ““ And cantbelistcount(i, j) =​ 7 Then

    putnumberpresent(i, j) =​ ““

    For putnumber =​ 1 To 9

      If findincantbelist(putnumber, i, j) =​ 0 Then

        putnumberpresent(i, j) =​ putnumberpresent(i, j) & putnumber

      End If

    Next putnumber

  End If

Now we check the entire row and add the pair to the cantbelist for those cells. As

you see below, it is done in three parts—​first part being from the first member of the

row to the cell before the first member of the pair (1 to k-​1), the second from the cell

straight after the first member of the pair to the one just before the second member

of the pair (k+​1 to i-​1), the third from the cell just after the second member of the

pair to the last cell of the row (i+​1 to 9).

  For k =​ 1 To i -​ 1

    If putnumberpresent(k, j) <> ““ And

      putnumberpresent(k, j) =​ putnumberpresent(i, j) Then

      For kk =​ 1 To k -​ 1

        Call addtocantbelist(Mid(putnumberpresent(k, j), 1, 1), kk, j)

        Call addtocantbelist(Mid(putnumberpresent(k, j), 2, 1), kk, j)

      Next kk

      For kk =​ k +​ 1 To i -​ 1

        Call addtocantbelist(Mid(putnumberpresent(k, j), 1, 1), kk, j)

        Call addtocantbelist(Mid(putnumberpresent(k, j), 2, 1), kk, j)

      Next kk

      For kk =​ i +​ 1 To 9

        Call addtocantbelist(Mid(putnumberpresent(k, j), 1, 1), kk, j)

        Call addtocantbelist(Mid(putnumberpresent(k, j), 2, 1), kk, j)

      Next kk

      Exit For

    End If

    Next k

  Next j

  Next i

STEP 12

The next step is to do the same for each column.

For i =​ 1 To 9

  For j =​ 1 To 9

    cantbelistcount(j, i) =​ 0

    For k =​ 1 To 9

      If cantbelist(j, i, k) <> 0 Then

        cantbelistcount(j, i) =​ cantbelistcount(j, i) +​ 1

      End If