This popular Japanese number puzzle has just one easy rule: In every Row, every Column and every 3x3 sub-grid, all the numbers from 1 to 9 should appear, but only once in each row, column and sub-grid.
+------+-------+------+
| 0 0 0 | 7 0 0 | 4 0 0 |
| 0 3 0 | 0 9 0 | 0 2 0 |
| 4 0 0 | 0 0 5 | 0 0 0 |
+------+-------+------+
| 0 0 8 | 0 0 0 | 0 0 5 |
| 0 9 0 | 0 3 0 | 0 7 0 |
| 6 0 0 | 0 0 0 | 3 0 0 |
+------+-------+------+
| 0 0 0 | 4 0 0 | 0 0 6 |
| 0 7 0 | 0 2 0 | 0 9 0 |
| 0 0 5 | 0 0 8 | 0 0 0 |
+------+-------+------+

Replace the 0's with the digits required to satisfy the rule.

(In reply to re(4): Haley's Comet vrs. Penny's Loafer: And the winner is.... by Charlie)

My same program (basically), run under the VB 5.0 IDE takes 2 min, 14 sec to find the 82 solutions of the modified problem, but when compiled, the .EXE takes 1 min, 10 sec.  on a 2 GHz processor.

Dim b(9, 9)
Dim solCt
Dim l$(9)

Private Sub cmdStart_Click()
Open "missing.txt" For Output As #2
Print Timer
For i = 1 To 9
 l$(i) = Choose(i, "000000400", "030090020", "400005000", "008000005", "090030070", "600000300", "000400006", "070020090", "005008000")
Next i
For i = 1 To 9
 For j = 1 To 9
  b(i, j) = Val(Mid$(l$(i), j, 1))
 Next
Next

find 1, 1
CurrentX = 2.5: CurrentY = 0.5
Print Timer, solCt
Close 2
End Sub
Sub find(v, h)
 DoEvents
 If b(v, h) = 0 Then
    x = 0: y = x
    For trial = 1 To 9
     good = 1
     For i = 1 To 9
       If b(v, i) = trial Or b(i, h) = trial Then good = 0
     Next i
     If good Then
       v1 = Int((v - 1) / 3) * 3 + 1
       h1 = Int((h - 1) / 3) * 3 + 1
       For i = v1 To v1 + 2
        For j = h1 To h1 + 2
         If b(i, j) = trial Then good = 0
        Next
       Next
       If good Then
          b(v, h) = trial
          GoSub incrCoords
          b(v, h) = 0
       End If
     End If
    Next trial
 Else
    GoSub incrCoords
 End If
 Exit Sub

incrCoords:
  hnew = h + 1
  If hnew > 9 Then
   vnew = v + 1: hnew = 1
  Else
   vnew = v
  End If
  If vnew > 9 Then
    For i = 1 To 9
     For j = 1 To 9
      Print #2, b(i, j);
     Next
      Print #2,
    Next
    solCt = solCt + 1
    Print Timer, solCt
  Else
    find vnew, hnew
  End If
 Return
End Sub

 

Posted by Charlie on 2005-05-16 14:50:46