Problem 18. Bullseye Matrix

Created by Cody Team

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Given n (always odd), return output a that has concentric rings of the numbers 1 through (n+1)/2 around the center point. Examples:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ Input  n = 3\n Output a is [ 2 2 2 \n               2 1 2\n               2 2 2 ]\n\n Input  n = 5\n Output a is [ 3 3 3 3 3\n               3 2 2 2 3 \n               3 2 1 2 3\n               3 2 2 2 3 \n               3 3 3 3 3 ]]]></w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Solve

Solution Stats

9138 Solutions
4399 Solvers

Last Solution submitted on Jul 23, 2021

Last 200 Solutions

Problem Comments

25 Comments

25 Comments

Show 22 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!!

Marlon Trujillo on 20 Sep 2020

Nice one....

Dzmitry Mukha on 11 Dec 2020

nice!

Solution Comments

Solution 5795178

Solution 4281040

1 Comment

1 Comment

Victoria Slawinski on 14 Dec 2020

Fun project!

Solution 2286146

1 Comment

1 Comment

Trusted on 16 May 2020

Adding comment for testing badges!!

Solution 2075072

1 Comment

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.

Solution 1986492

1 Comment

1 Comment

Asif Newaz on 22 Oct 2019

nic problem..it was fun

Solution 1852965

2 Comments

2 Comments

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?

Adria de Juan Garcia on 31 Mar 2021

That's probably because padarray() needs Image Processing Toolbox which is not implemented in Cody.

Solution 1371552

1 Comment

1 Comment

Connor O'Grady on 6 Dec 2017

Wow, this wasn't easy for me

Solution 1204954

3 Comments

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

Solution 1194270

1 Comment

1 Comment

Informaton on 21 May 2017

This is the actual, sans regexp, size of the leading solution: 25

Solution 1044893

1 Comment

1 Comment

auto2060 on 5 Nov 2016

The ans is amazing.Contrast to my last solution,the size add 2.
This solution is from online froum.

Solution 989769

1 Comment

1 Comment

Lucas Valle on 3 Oct 2016

my solution clearly works on my matlab. not here. wonder why

Solution 960810

1 Comment

1 Comment

Jim Myers on 6 Sep 2016

Shame you can't use padarray.

Solution 785797

2 Comments

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.

Solution 678011

2 Comments

2 Comments

Varoujan on 31 May 2015

I checked the above function against the two cases below and it produces correct result yet the test shows failed. I think the test is broken.

bainhome on 31 May 2015

"padarray" is not allowed to use in sever.that's why.

Solution 593338

1 Comment

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 :)

Solution 444553

2 Comments

2 Comments

Omer on 3 Jun 2014

hehe cheeky alert

Alvery on 13 Jul 2014

Perhaps a little pointless just reproducing the test case?

Solution 357394

1 Comment

1 Comment

Alican Bozkurt on 21 Nov 2013

no image processing toolbox then?

Solution 355688

2 Comments

2 Comments

Emilio on 19 Nov 2013

:P yeah, I know...

Douglas Knox on 26 Feb 2014

hahahah

Solution 343984

2 Comments

2 Comments

niu on 2 Mar 2014

brilliant!

Arnaud on 14 Apr 2016

Very nice, well done.

Solution 261083

3 Comments

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 -*-

Solution 249294

1 Comment

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?

Solution 234331

1 Comment

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.

Solution 192991

1 Comment

1 Comment

Jerome on 18 Jan 2013

Not fair :(

Solution 183039

1 Comment

1 Comment

Nicholas Hortance on 19 Aug 2015

wow

Problem Recent Solvers4399

Problem Tags

matrices

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 18. Bullseye Matrix

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers4399

Suggested Problems

More from this Author95

Problem Tags

Community Treasure Hunt

Problem 18. Bullseye Matrix

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers4399

Suggested Problems

More from this Author95

Problem Tags

Community Treasure Hunt

Players