Problem 44311. Number of Even Elements in Fibonacci Sequence
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Problem Comments

6 Comments
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.
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'
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.
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
Not a hard problem at all lol
The Tran Tran comment is the key to solve the problem.
Solution Comments

1 Comment
comments will guide you

3 Comments
Hahaha funny, proof that math is the shortcut
Good solution
Math is a hack.

1 Comment
@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.

1 Comment
it is working in my Matlab

1 Comment
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.

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

3 Comments
What's wrong with this?? It's working in matlab for me .
me2
The fibonacci() function is in a toolbox. Only functions in vanilla Matlab are recognized by Cody.

4 Comments
My code works to d=50 and fails on the higher values in the test suite. I think it is a hardwarelimited 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.
Leo, your theory is correct: The numbers that you're calculating for d>50 are too large to be represented by a 32bit 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.
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.
me too.

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

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