Problem 51. Find the two most distant points

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 a collection of points, return the indices of the rows that contain the two points most distant from one another. The input vector p has two columns corresponding to the x and y coordinates of each point. Return ix, the (sorted) pair of indices pointing to the remotest rows. There will always be one unique such pair of points.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>So if</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ p = [0 0]\n     [1 0]\n     [2 2]\n     [0 1]]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Then</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[ ix = [1 3]]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>That is, the two points p(1,:) and p(3,:) are farthest apart.</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

4027 Solutions
1766 Solvers

Last Solution submitted on May 07, 2021

Last 200 Solutions

Problem Comments

6 Comments

6 Comments

Show 3 older comments

Jean-Marie Sainthillier on 19 Jul 2012

More easy that it seems.

Carl Witthoft on 20 Nov 2015

You need to specify "Euclidean" distance :-)

Jerivington on 6 Jun 2016

Good problem, not too hard but required thinking

Dima Panna on 3 Jun 2019

Please add the next test :
p = [0,0;
2,1;
2,6;
1,6];
ix_correct = [1 3];
assert(isequal(mostDistant(p),ix_correct))

The solutions of the form:
[~,indx]=max(dist(p'));
unique(indx)

will fail, the last line will return an extra index [1,3,4] instead of just [1,3]

heart on 8 Feb 2020

refer to
Convex Hull therom and the Graham's Scan method

Can Tekin on 12 Jun 2020

Solution Comments

Solution 2570352

1 Comment

1 Comment

Shams Rashid on 16 Jun 2020

hehe, just trying to see if they have any hidden tests for the code.

Solution 1813949

2 Comments

2 Comments

Qiaoli Xie on 13 May 2019

Since yesterday, I submit the solution ,and it always shows "
While evaluating the solution, the server encountered an error caused by temporary unavailability of MATLAB Service. Wait a few minutes for the MATLAB Service to return, and then rescore."
I don't know how to deal with it?

Isha Desai on 13 May 2019

You should be able to submit solutions now. Sorry for the inconveniene.

Solution 1790572

2 Comments

2 Comments

Paul Smits on 16 Apr 2019

no function squareform either... pffff

goc3 on 22 Apr 2019

Cody utilizes vanilla MATLAB (no toolboxes).

Solution 1790541

1 Comment

1 Comment

Paul Smits on 16 Apr 2019

Why is there "undefined function 'dist' for input arguments of type 'double'."? Works on my machine (and online matlab too)

Solution 1577123

1 Comment

1 Comment

Luyu Wang on 6 Jul 2018

I solved the problem by an tedious approach.

Solution 1050564

1 Comment

1 Comment

auto2060 on 11 Nov 2016

remove ' diff ',but adds size -_-

Solution 903112

1 Comment

1 Comment

Jerivington on 6 Jun 2016

:)))))

Solution 393335

1 Comment

1 Comment

priyanka shrivastava on 7 Feb 2014

I am using matlab2010 but dist function is not available in it. Can you tell me how and where can I use this?

Solution 387795

2 Comments

2 Comments

Jon on 17 Jan 2014

Without dist, but with str2num

Carl Witthoft on 23 Nov 2015

I think it works w/ just x*[1;i] . No need to convert from a string.

Solution 267361

1 Comment

1 Comment

Mineralter on 26 Jun 2013

i'm not sure this can always get the right answer,
so i need more debugging.

Solution 151481

2 Comments

2 Comments

Claudia on 16 Nov 2012

what is 'i'? This is strange but works.

Ned Gulley on 16 Nov 2012

@Claudia, "i" is the imaginary number sqrt(-1). Unless you overwrite it, it's always available to you in MATLAB without needing to declare it.

Solution 129842

1 Comment

1 Comment

Jamie Rodgers on 22 Aug 2012

Excuse me?
This solution works fine, but requires the stats toolbox to function!

Solution 116870

4 Comments

4 Comments

Show 1 older comment

Tony on 18 Feb 2013

I dont get whay sort(unique(ix)) will give you the location of the two points. it is wrong for these points (0.9631 0.5468),(0.5211 0.2316),(0.4889,0.6241),(0.6791 0.3955),(0.3670 0.9890),
sort(unique(ix)) will return [1 2 5].

li jian on 23 Mar 2013

I think this solution is not right

Khaled Hamed on 24 Mar 2013

I agree.

Mineralter on 26 Jun 2013

there may be something out of word,
if i put:
p =[1 0; 0 1;0 0; 1/sqrt(2) 1/sqrt(2) ]
your command would not right,
but 'unique' is very admirable.

Solution 113745

1 Comment

1 Comment

Heather on 29 May 2013

This is the smallest solution not to use "dist," which is not in core Matlab. Nicely done!

Solution 81500

1 Comment

1 Comment

Carl Witthoft on 23 Nov 2015

I don't know why Cody allows answers which depend on toolboxes. The whole point should be to write one's own "distance" function.

Solution 38083

1 Comment

1 Comment

Clive Hayward on 12 Feb 2012

Hard to believe you let 'dist' in but not 'pdist'.

Solution 38081

1 Comment

1 Comment

Clive Hayward on 12 Feb 2012

pdist is not allowed!

Solution 29161

1 Comment

1 Comment

Jean-Yves Tinevez on 10 Feb 2012

I find this a little bit unfair: dist is a neural network toolbox function. It is not available in MATLAB core, and the problem does not specify this toolbox is needed.

Solution 6849

1 Comment

1 Comment

Tim on 26 Jan 2012

Shame on me...

Problem Recent Solvers1766

Problem Tags

distance

Community Treasure Hunt

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

Start Hunting!

Problem 51. Find the two most distant points

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers1766

Suggested Problems

More from this Author95

Problem Tags

Community Treasure Hunt

Problem 51. Find the two most distant points

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers1766

Suggested Problems

More from this Author95

Problem Tags

Community Treasure Hunt

Players