Given n (always odd), return output a that has concentric rings of the numbers 1 through (n+1)/2 around the center point. Examples:
Input n = 3
Output a is [ 2 2 2
2 1 2
2 2 2 ] Input n = 5
Output a is [ 3 3 3 3 3
3 2 2 2 3
3 2 1 2 3
3 2 2 2 3
3 3 3 3 3 ]
Solution Stats
Problem Comments
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23 Comments
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20 older comments
Jan
on 19 Feb 2012
The image processing toolbox is not available!
Aritra Chatterjee
on 2 Jan 2013
A fantastic 1... calculate based on d distance of each element 4m central 1...
Shaun VanWeelden
on 1 Mar 2013
I see that now Jan, this stinks!
Jonathan
on 25 Jun 2013
Nice Problem!
Mineralter
on 28 Jun 2013
I have a question about why I can't use bwdist to generate the chessboard matrix?
Image Processing ToolBox is not allowed?
Chris Cleveland
on 14 Oct 2013
Fun problem!
asif iqbal
on 10 Nov 2013
Interesting problem
Pritesh Shah
on 18 Aug 2014
good problem. What is use of this matrix?
Thomas
on 16 Dec 2014
Like this one!!
Tyler Sproule
on 6 Mar 2015
Had lots of fun figuring it out
Moiz
on 8 Aug 2015
Hi guys,
Any one know how can you view a solution with lesser size than the one you submitted ?
Pradeep Miriyala
on 8 Oct 2015
Interesting one
Xiaoli Zhang
on 20 Aug 2016
never have the chance to see how people did it with less than 10 size
David Browne
on 20 Sep 2016
Solving another cody problem you will enable you to see all the solutions to a this problem, and so learning can take place :)
Lucas Valle
on 3 Oct 2016
why does my solution work on matlab and not here?
Anoop Varghese
on 4 Apr 2017
Very challenging problem
Nirav Ambaliya
on 6 Jul 2017
Best problem out of those I solved till now.
Rathin Joshi
on 4 Apr 2018
I have tried using padarray. Its working totally fine with my MATLAB R2017b, but this shows undefined function. Why? Which version cody compiler is compatible with?
Mohammad Abir Hassan Sarker
on 11 Apr 2018
Simple Problem, but work out a lot for it, in the end I find the solution too simple. But great thing is I've learned a lot from it.
Jie LONG
on 18 Apr 2018
wow
Aakash Deep
on 14 May 2018
Nice problem. I like such matrix problems.
Siriniharika Katukam
on 11 Mar 2019
Nice One
Sanzhar Askaruly
on 13 Jun 2019
Love it!!
Solution Comments
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1 Comment
Trusted
on 16 May 2020 at 12:12
Adding comment for testing badges!!
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1 Comment
Raymond MacNeil
on 31 Dec 2019
A lot easier than I originally anticipated. Once you start setting up the problem variables, it comes together pretty easily.
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1 Comment
Asif Newaz
on 22 Oct 2019
nic problem..it was fun
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1 Comment
Willion Bird
on 19 Jun 2019
function a = bullseye(n)
a = 1;
for i = 2:(n+1)/2
a = padarray(a, [1,1], i, 'both');
end
end
Why doesn't this function work?
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1 Comment
Connor O'Grady
on 6 Dec 2017
Wow, this wasn't easy for me
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3 Comments
Ionut Barbu
on 24 Jul 2017
clever!
Gustavo Morales
on 15 Nov 2019
Should be the best for now!
Bryan Lambo
on 17 Jan 2020
nice! didn't know about discretize til i saw this solution
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1 Comment
Informaton
on 21 May 2017
This is the actual, sans regexp, size of the leading solution: 25
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1 Comment
yao gang
on 5 Nov 2016
The ans is amazing.Contrast to my last solution,the size add 2.
This solution is from online froum.
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1 Comment
Lucas Valle
on 3 Oct 2016
my solution clearly works on my matlab. not here. wonder why
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1 Comment
Jim Myers
on 6 Sep 2016
Shame you can't use padarray.
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2 Comments
Adr Paw
on 10 Aug 2016
it's very nice solution, but sadly it's not general solution
Peng Liu
on 11 Aug 2016
My original objective was to reduce the Cody size as much as possible. You can make this solution general by using y = discretize(spiral(n), [0 1:2:n].^2+.5) or y = discretize(spiral(n), [0 1:2:n].^2, 'IncludedEdge','right'), which has a higher size though.
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2 Comments
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1 Comment
E. Cheynet
on 7 Mar 2015
more elegant solution than a loop: Use the LDL decomposition on the bullseye matrix and you will find an interesting L and D matrix. THe D matrix is diagonale and can be built using n only. THe matrix L is the sum of a lower triangular matrix whose lowest part is put to zero using the mirrored triangular matrix. Finally the identity matrix is added :)
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2 Comments
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1 Comment
Alican Bozkurt
on 21 Nov 2013
no image processing toolbox then?
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2 Comments
Emilio
on 19 Nov 2013
:P yeah, I know...
Douglas Knox
on 26 Feb 2014
hahahah
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2 Comments
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3 Comments
Christos Papoulas
on 21 Jun 2013
funny code!
Edgar Guevara
on 28 Sep 2013
Not exactly a general solution...
avancer
on 25 Oct 2013
Tester -*-
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1 Comment
Adam
on 26 May 2013
This would work if it recognized 'padarray'. Is cody using an older or more spartan version of matlab?
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1 Comment
James Kristoff
on 12 Oct 2013
Solutions like this are tricky. It would be nice if we could all agree as a community that this is not a valid way to reduce the size of a solution.
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1 Comment
Jerome
on 18 Jan 2013
Not fair :(
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1 Comment
Nicholas Hortance
on 19 Aug 2015
wow
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