Find how many even Fibonacci numbers are available in the first d numbers.
Consider the following first 14 numbers
1 1 2 3 5 8 13 21 34 55 89 144 233 377 ...
4 of them are even.
Solution Stats
Problem Comments
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1 Comment
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.
Solution Comments
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2 Comments
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.
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1 Comment
David Verrelli
on 3 Nov 2017
Not a true solution. Would fail if Test Suite were expanded.
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1 Comment
David Verrelli
on 3 Nov 2017
Not a general solution. Will fail if Test Suite expanded.
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