Problem 232. Project Euler: Problem 2, Sum of even Fibonacci

Created by Dyuman Joshi

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<div style = "text-align: start; line-height: 20.4333px; min-height: 0px; white-space: normal; color: rgb(0, 0, 0); font-family: Menlo, Monaco, Consolas, monospace; font-style: normal; font-size: 14px; font-weight: 400; text-decoration: rgb(0, 0, 0); white-space: normal; "><div style="block-size: 123px; display: block; min-width: 0px; padding-block-start: 0px; padding-top: 0px; perspective-origin: 407px 61.5px; transform-origin: 407px 61.5px; vertical-align: baseline; "><div style="block-size: 42px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 21px; text-align: left; transform-origin: 384px 21px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 384px 8px; transform-origin: 384px 8px; unicode-bidi: normal; "><span style="">Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:</span></span></div><div style="block-size: 21px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 10.5px; text-align: left; transform-origin: 384px 10.5px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 106px 8px; transform-origin: 106px 8px; unicode-bidi: normal; "><span style="">1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...</span></span></div><div style="block-size: 42px; font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 384px 21px; text-align: left; transform-origin: 384px 21px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; "><span style="block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 367px 8px; transform-origin: 367px 8px; unicode-bidi: normal; "><span style="">By considering the terms in the Fibonacci sequence whose values do not exceed the input value, find the sum of the even-valued terms.</span></span></div></div></div>

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Solution Stats

5728 Solutions
1486 Solvers

Last Solution submitted on May 19, 2022

Last 200 Solutions

Problem Comments

5 Comments

5 Comments

Show 2 older comments

Aurelien Queffurust on 20 Feb 2012

I wanted to use : z = feval(symengine,'numlib::fibonacci',10)
to get the 10th element for example but CODY returns:
Could not check out Symbolic Math Toolbox license.

pas de chance!

yurenchu on 13 Mar 2017

You should add test cases where x or x+1 equals an even fibonacci number (either small or large).

Majid Farzaneh on 15 Oct 2018

Nice problem. I always have problem with big numbers.

Mehdi BENSEDDIK on 10 Apr 2019

I solved the problem until x = 4000000 but x = 97455000 it gives me an error of exceeding the memory(overflow) because the number is too large.

Revathe Thillaikumar on 8 May 2022 at 6:51

This was fun!

Solution Comments

Solution 7682544

4 Comments

4 Comments

Show 1 older comment

Tran Tran on 12 Mar 2022

I only generate the even numbers.Its save my solution a lot of time.My solution bases on algolithrim
E(N) = 4 * E(N-1) + E(N-2)

where E(0) = 2 and E(1) = 8

Dyuman Joshi on 12 Mar 2022

You might wanna try again

Tran Tran on 12 Mar 2022

Wow thank for advise I dont think x =2 make my loop not work.Your additional test case make me change.

Jose Matos on 29 Mar 2022

Tran Tran, thanks for the tip. Your formula to to calculate just the even Fibonacci numbers really work. Thanks!

Solution 3087836

1 Comment

1 Comment

Akrem Hadji on 6 Oct 2020

the last value x = 666576 the correct answer should be 574925

Solution 3028933

1 Comment

1 Comment

Marius Mueller on 2 Oct 2020

My solution works fine on my Laptop unter R2015b. Nevertheless i get the error:
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.

Solution 1941246

1 Comment

1 Comment

Lingjun Ding on 11 Jan 2021

nice

Solution 1759649

1 Comment

1 Comment

Mohammad Hossein Zardary on 26 Nov 2020

Cheat!!!!!!!!!!

Solution 1586878

1 Comment

1 Comment

Ankith Rathod on 19 Jul 2018

y is it not working when it even works on octave and get results in a sec

Solution 1586868

1 Comment

1 Comment

Ankith Rathod on 19 Jul 2018

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.

those test numbers are too big

Solution 1287182

1 Comment

1 Comment

Jitesh Kumar on 15 Oct 2017

it is correct but by server error its not showing

Solution 216651

2 Comments

2 Comments

Harish Maradana on 13 Mar 2013

test for cheating

Tran Tran on 12 Mar 2022

CHEATER !!!!

Solution 76573

2 Comments

2 Comments

Peter Wittenberg on 14 Apr 2012

OK, I gamed this one so it only works up to about 1 billion. I wanted to see everyone else's interesting solutions.

Revathe Thillaikumar on 8 May 2022 at 6:51

You can first generate the even fibonacci numbers for the given first two elements (here, 1 and 2) till they reach x, then sum the calculated even numbers (that are less than or equal to the input value x).

Solution 26585

2 Comments

2 Comments

Alfonso Nieto-Castanon on 3 Feb 2012

this trick (c.f. Solution 26456) works only for these particular test cases, it would fail for example with euler002(6)...

Ankith Rathod on 19 Jul 2018

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.

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fibonacci projecteuler

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Problem 232. Project Euler: Problem 2, Sum of even Fibonacci

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Problem 232. Project Euler: Problem 2, Sum of even Fibonacci

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Last 200 Solutions

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Problem Recent Solvers1486

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