Problem 2024. Triangle sequence

Created by Tanya Morton

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Solution Stats

6614 Solutions
2149 Solvers

Last Solution submitted on Jan 27, 2021

Last 200 Solutions

Problem Comments

27 Comments

27 Comments

Show 24 older comments

Jean on 12 Dec 2013

good for brain !

Jean-Marie Sainthillier on 13 Dec 2013

The best problem of the CUP challenge.

Jean-Marie Sainthillier on 13 Dec 2013

I think that thematic challenge is a wonderful idea. I solved this one with a great pleasure.

Matt on 4 Feb 2014

Great problem. So many ways to solve it. It was fun trying different methods to see which scored the best.

Daniel lefebvre on 8 Feb 2014

The connection of this problem with the Fibonacci sequence is most interesting.

Philipp on 5 Mar 2014

indeed: like!

Guilherme Coco Beltramini on 26 Jun 2014

Very interesting problem!

Vishal on 8 Sep 2014

Interesting problem....!

Vidushi Jain on 10 Jun 2015

Interesting!!

Pooja Narayan on 23 Feb 2016

Good one :)

Giovanni Mottola on 7 Jun 2016

Combining the Fibonacci sequence and the Pythagorean theorem is a nice idea

Dhaval on 11 Sep 2016

I thought I had the right code and it didn't work. Then I realized that the area of the first triangle (n=1 case) should be 0.5*4*3 = 6. But is given in the solution as 25. Am I understanding this wrong? I thought the three sides of the first triangle (n=1) was 3,4,5 and we go on from there. Please let me know if my understanding is wrong and then I can proceed Otherwise I have a general code.

Milan Petrovic on 21 Oct 2016

@ Dhaval: Try reading the last sentence of the problem very carefully.

Dhaval on 10 Dec 2016

@Milan Petrovic: Thank you, I completely missed that; silly me. Now I got it to work :)

Joao Vitor Monteiro Lopes on 17 Jun 2017

Good problem. Kinda fun too.

Chris Eio on 13 Oct 2017

Definitely needed to read that last line carefully. Like at least one other here, I misread it.

Anthony Cafeo on 28 Nov 2017

can someone help me with this problem?

Wycliff Dembe on 26 Aug 2018

tough but fun... had issues with assertion at first through

Zhilin Ye on 6 Jan 2019

Does Cody not recognize the Fibonacci function?

Anthony Zúñiga on 16 Jan 2019

Can anybody PLEASE send me the solution of this problem? My e-mail is: anthonydavid72@hotmail.com

Dani Péter on 20 Apr 2019

so interesting!

Christian Schröder on 8 Jul 2019

Nice one! Makes you think, and then the solution is simple and elegant.

Parv Verma on 6 Dec 2019

It was a really great problem to solve. For me doing the steps as mentioned on paper helped a lot for proper visualization of the problem, and to understand the flow.
Thanks Tanya Morton for the problem exercise.

Ahmet Burak Aydogdu on 18 Apr 2020

Very elegantly done!

carlos fuentes on 25 Apr 2020

Very very interesting problem. It introduces the importance of integer sequences.

Jaya Lee on 2 Aug 2020

Why I cannot use the matlab's fibonacci function here? It was Introduced in R2017a. My local PC's matlab and moble matlab can work it out well. Kind of strange.

goc3 on 29 Sep 2020

@Jaya Lee: Cody does not support toolbox functions.

Solution Comments

Solution 4359065

1 Comment

1 Comment

song peng on 19 Dec 2020

Nice!

Solution 2777821

1 Comment

1 Comment

Alex Wu on 5 Aug 2020

Interesting way to solve

Solution 2674229

1 Comment

1 Comment

Umur Ulas Harman on 10 Jul 2020

function area = triangle_sequence(n)

y(1)=3;
y(2)=4;

for i=1:n
y(i+2)=sqrt(y(i)^2+y(i+1)^2)
end
area = y(n+2)^2;
end

Solution 2590360

1 Comment

1 Comment

Piero Cimule on 21 Jun 2020

C=[3,4,5];
for i=2:n
C(end+1,1,1)=C(end,2,1);
C(end,2,1)=C(end-1,3,1);
C(end,3,1)=sqrt(C(end,1,1)^2+C(end,2,1)^2);
end

C= [C(end,:,1)]
area=C(3)^2

Solution 1947062

1 Comment

1 Comment

Chris Guenther on 24 Sep 2019

Dear Cody Team,
solutions like mine shall be not allowed.

Solution 1780440

1 Comment

1 Comment

Chris Coote on 10 Apr 2019

Elegant brain teaser and a good reminder to always read the question carefully...

Solution 1730996

2 Comments

2 Comments

Rafael S.T. Vieira on 3 Jun 2020

And now, nobody will ever see it. You should have, at least, posted it.

RAJESH GANGIREDDY on 9 Nov 2020

Can you please delete this answer?
When I click on "leading solution", I get this solution, which is of no use.

Solution 1711544

1 Comment

1 Comment

James Best on 21 Jan 2019

Seems broken, when using Fibonacci ratio it won't work so I have botched it instead

Solution 1645520

1 Comment

1 Comment

reyhane mohebali on 14 Oct 2018

So Exciting !

Solution 1604655

1 Comment

1 Comment

Othmane ELMOUATAMID on 9 Aug 2018

Finally made it :D ... Fibonacci sequence !

Solution 1587052

1 Comment

1 Comment

durga sadasivuni on 19 Jul 2018

please help me out in understanding the problem

Solution 1553015

1 Comment

1 Comment

durga sadasivuni on 7 Jun 2018

Didn't understand question

Solution 1482114

1 Comment

1 Comment

Rachel Wedemeyer on 6 Apr 2018

very hard example
R_T=[3 4 5];
if (n>1)
for i=1:(n-1)
R_T=[R_T(2) R_T(3) (R_T(2)^2+R_T(3)^2)^0.5]

Solution 1412892

1 Comment

1 Comment

Thiago César on 10 Jan 2018

Attention to the last line!

Solution 1269220

1 Comment

1 Comment

ccljohn123 on 16 Sep 2017

Double fibonacci sequence, subtle! I love this problem!

Solution 962178

1 Comment

1 Comment

Thomas Blackwood on 7 Sep 2016

If anyone cares to point out why this is wrong, I'm open to hearing.

Solution 939320

1 Comment

1 Comment

John D'Errico on 21 Aug 2016

Note that the ratio of consecutive areas is asymptotically the golden ratio, i.e., phi=(1+sqrt(5))/2.

Solution 924080

1 Comment

1 Comment

Daniel Zimmermann on 16 Jul 2016

Weak! My recursion solution should work just fine, but the server is unable to evaluate it properly. I'm going to count it.

Solution 848081

2 Comments

2 Comments

Carlos Zúñiga on 9 Mar 2016

Its the best way that I found :)

Suraj Gurav on 3 Sep 2018

I think it is the only way to solve this Problem. We Need to get the sides of nth triangle and ist done.

Solution 420475

2 Comments

2 Comments

Raphael on 20 Mar 2014

I consider my answer as a cheat

Shuvo Kumar Paul on 5 Aug 2020

Yeah, you have just copied the required values of the test suits.

Solution 396992

3 Comments

3 Comments

Bruce on 1 Apr 2015

Interesting... (not a reflection on this particular solution but cody in general) - most of the lowest scored answers could be entries in an "obfuscated code" contest.

Eugen Zimmermann on 23 May 2018

I'm curious how all these "Size 10" solutions look like. I don't get even close to this value. I terms of education, it would be great to see example codes which are able to go this low.

Othmane ELMOUATAMID on 9 Aug 2018

Brilliant !

I join you @Eugen, it would be great to share some "Size 10" solutions samples.

Solution 396181

1 Comment

1 Comment

Jon on 3 Feb 2014

yes, this is probably cheating

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Problem Tags

fibonacci pythagoras

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Problem 2024. Triangle sequence

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Problem 2024. Triangle sequence

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