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In a Mystery.... (Posted on 2009-04-16) Difficulty: 4 of 5

                    ..... we might expect some:


Each button (1-9) will display at least one letter in the 'LED' window. Note also that if two or more buttons control a cell, and are activated, then a displayed letter will change.

A switch is 'ON' when its indicator (right) changes from [O] to [ I ].

Find four 10-letter words which could complete the sentence.

See The Solution Submitted by brianjn    
Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
The only computer use is a little help from Gray | Comment 11 of 12 |
(In reply to Listing words by Jer)

Only 512 button presses (or rather 511, as the last only returns to the starting position) it's possible to see all the possibilities, if the buttons are pressed in the following sequence:

1213121412131215121312141213121612131214121312151213121412131217
1213121412131215121312141213121612131214121312151213121412131218
1213121412131215121312141213121612131214121312151213121412131217
1213121412131215121312141213121612131214121312151213121412131219
1213121412131215121312141213121612131214121312151213121412131217
1213121412131215121312141213121612131214121312151213121412131218
1213121412131215121312141213121612131214121312151213121412131217
1213121412131215121312141213121612131214121312151213121412131219

 

They are the changed bits in a Gray code sequence for 9 bits. To aid in keeping track, I only used the following VB 5 code:

Dim sw(512)
Dim ptr
Private Sub Command1_Click()
 ptr = ptr + 1
 lblNumber.Caption = Str(sw(ptr))
End Sub

Private Sub Form_Load()
 evry = 1
 For i = 1 To 9
  For j = evry To 512 Step evry
   sw(j) = i
  Next
  evry = evry * 2
 Next
End Sub

The only problem is making sure one hits the button on the head to avoid accidentally missing one, taking one backward along the way.

Edited on April 16, 2009, 4:01 pm
  Posted by Charlie on 2009-04-16 15:57:21

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