Problem 44311. Number of Even Elements in Fibonacci Sequence

Created by Mehmet OZC

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4516 Solutions
966 Solvers

Last Solution submitted on Nov 28, 2022

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6 Comments

6 Comments

Show 3 older comments

Ren Liujie on 22 Dec 2017

Big number is a problem. Instead we can find the regular pattern in which those even and odd numbers appear. Then everything becomes simple and easy.

Highphi on 26 Jul 2020

Gorgeously simple once you figure it out
hint: copy and paste the first few test suites into your MATLAB console and try plotting it with ':o'

Jiseon Shin on 28 Oct 2020

My solution is working in my local computer but is not consistent with Test Suites starting from d = 100. I don't still get the answer.

Tran Tran on 11 Mar 2022

You dont need generate all d fibonacci number to find the numbers of even.Think like that 2 odd fibonacci numbers will make a even number
like 1 1 make 2, and 3 5 make 8.So 3 numbers in group will have a even number

Pisces on 12 Jul 2022

Not a hard problem at all lol

Ricardo on 13 Nov 2022 at 22:09

The Tran Tran comment is the key to solve the problem.

Solution Comments

Solution 8471320

3 Comments

3 Comments

Ilya Dikariev on 1 Jun 2022

Hahaha funny, proof that math is the shortcut

Vaishnavi Jayavant on 12 Jul 2022

Good solution

John on 13 Jul 2022

Math is a hack.

Solution 5177606

1 Comment

1 Comment

goc3 on 29 Mar 2021

@Kashfia Rahman Oyshei: your comment was deleted, as it revealed a potential solution. Regarding your solution failing at large values of d, look at other comments to the problem for hints.

Solution 3658988

Solution 3197881

1 Comment

1 Comment

Asrorkhuja Ortikov on 13 Oct 2020

it is working in my Matlab

Solution 2714223

1 Comment

1 Comment

Mohamed AIDAHI on 20 Jul 2020

i'm pretty confident of my code but it doesn't work for d>= 100 due to the lack of percision since it surpasses the capability of double and uint64 so you can't test if the number is even.

Solution 2495075

1 Comment

1 Comment

Sivaramarao B on 8 Jun 2020

I think there is a bug in the assertions after 4th one

Solution 1865516

3 Comments

3 Comments

SJ Won on 4 Jul 2019

What's wrong with this?? It's working in matlab for me .

Lamour Haithem Firass on 21 Sep 2019

me2

goc3 on 23 Oct 2019

The fibonacci() function is in a toolbox. Only functions in vanilla Matlab are recognized by Cody.

Solution 1319950

4 Comments

4 Comments

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Leo Nunnink on 30 Oct 2017

My code works to d=50 and fails on the higher values in the test suite. I think it is a hardware-limited rounding error (?swamping) with very large numbers. When I test eps(fibonacci(100)) on my system, the answer is 6.5 ie my system can not accurately distinguish odd from even at that large a number.

James on 2 Nov 2017

Leo, your theory is correct: The numbers that you're calculating for d>50 are too large to be represented by a 32-bit digit, and won't be calculated correctly for mod(x,2). Think very carefully about the number pattern in the Fibonacci sequence, and see if a pattern emerges.

Mehdi BENSEDDIK on 4 Apr 2019

Indeed, My code works until the d = 50 because it's a large number, so our algorithm is correct we should not worry about it, I think we have succeed in this challenge.

Behnaz Zirakkar on 22 May 2022

me too.

Solution 1318351

1 Comment

1 Comment

David Verrelli on 3 Nov 2017

Not a true solution. Would fail if Test Suite were expanded.

Solution 1302521

1 Comment

1 Comment

David Verrelli on 3 Nov 2017

Not a general solution. Will fail if Test Suite expanded.

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Problem 44311. Number of Even Elements in Fibonacci Sequence

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Problem 44311. Number of Even Elements in Fibonacci Sequence

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