Puzzle Corner

Ezra Pound

Well-Known Member
As the festive season is upon us, I though I would submit a puzzle, it was though up by the GCHQ staff


GCHQ-Puzzle.JPG


Explaining how to get started, the GCHQ website states: "In this type of grid-shading puzzle, each square is either black or white. Some of the black squares have already been filled in for you.

"Each row or column is labelled with a string of numbers. The numbers indicate the length of all consecutive runs of black squares, and are displayed in the order that the runs appear in that line.

"For example, a label "2 1 6" indicates sets of two, one and six black squares, each of which will have at least one white square separating them."

Puzzle website link here :-
http://www.gchq.gov.uk/SiteCollectionImages/grid-shading-puzzle.jpg

First thoughts, it would be possible to write a program to 'score' every possible combination of black on white squares, however my calculator won't tell me what 2's 625th power is, so I'm guessing it's not a small number :)
EDIT
It's 1.392346 e+188 combinations for the whole square, I think calculating single rows at 33,554,432 combinations could be done, but there will be more than one solution for a single row/column - Doh ! !
 
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Luke

Well-Knwοn Мember
First thoughts, it would be possible to write a program to 'score' every possible combination of black on white squares, however my calculator won't tell me what 2's 625th power is, so I'm guessing it's not a small number :)
EDIT
It's 1.392346 e+188 combinations for the whole square, I think calculating single rows at 33,554,432 combinations could be done, but there will be more than one solution for a single row/column - Doh ! !
There are some very easy bits here. Column 17 for a start! That should start to cut down the sledge hammer approach

What I am having difficulty is with locating the site's page that has the instructions!
 

Black Hole

May contain traces of nut
I thin this looks interesting, a bit different from the usual Sudoku (no matter how fiendish). I'll let you know...
 
OP
Ezra Pound

Ezra Pound

Well-Known Member
It's early days but, I think I see a familiar pattern to the blocks, something that could be scanned?
 

Black Hole

May contain traces of nut
Not finished yet, but I concur. I wonder where it will lead!

Bugger. I have to do something else now, no doubt you'll all have finished it by the time I get back.
 
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Black Hole

May contain traces of nut
Solved. It seems to link to another puzzle, but the web page is taking ages to load.

Update: Part 2 is a series of multiple choice questions, and it says there is a part 3.
 
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Luke

Well-Knwοn Мember
Solved. It seems to link to another puzzle, but the web page is taking ages to load.

Update: Part 2 is a series of multiple choice questions, and it says there is a part 3.

One of the news reports stated it was a series of puzzles with the final having contact details.
 

Black Hole

May contain traces of nut
I am curious whether the matrix is solvable without the seed squares. Not sure I'm going to do it again to find out!
 

Black Hole

May contain traces of nut
I've been thinking about this for a day, but can't get it. I have narrowed it down to two:

(The problem is paradoxical: if there is one which is not the odd one out, then it must also be unique for that and therefore the odd one out... does that mean the answer is a pair of them?)

image.jpg
 

Luke

Well-Knwοn Мember
I am curious whether the matrix is solvable without the seed squares. Not sure I'm going to do it again to find out!
Even without training in computability and unsolvability theory surely it is a doddle to work out "whether the matrix is solvable without the seed squares"!

There are a finite number of possible ways to complete the matrix with black and white squares.
We already know that there is solution.
Therefore by trying each one in turn eventually that solution, (and any other solutions should there be others), can be identified, even if you did not know a solution to start off with.
QED. I.e. It is solvable
 

prpr

Well-Known Member
D is an odd one out because the double letters are in 4,5 not 3,4
So that leaves F.
 

Luke

Well-Knwοn Мember
D is an odd one out because the double letters are in 4,5 not 3,4
So that leaves F.
IMO that's getting a bit complicated and ignores A.
I think the question was supposed to be simple and literal without the BH enhancement.
 
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