Problem 002

[newinkles]

In the problem it says the sum of the even valued terms that do not exceed 4million. But the answer is the first term over 4 million. This might need to be reworded.

Nathan

[hk]

Why should the sum of the even valued fibonacci numbers less than 4 million not exceed 4 million?
The first fibonacci number that exceeds four million is 5702887. And that's not the correct answer.

So the individual terms to add must be less than 4 million, the sum does not need to be.

[kinyel]

Hello
I'm french (nobody's perfect... ) and my english is bad ...
and I don't understand really
"Find the sum of all the even-valued terms in the sequence which do not exceed four million."
what is "even valued" ? why not only "all terms" ?
please can someone translate in french, or (better ?) give me the wanted sum for the first 10 terms for example ...
( 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 )
I can't solve this problem even if I've solve 20 others problems yet

thanks for help !

[hk]

even numbers are numbers divisible by 2.
So you are asked to sum the Fibonacci numbers less than 4 million that are divisible by 2.

[kinyel]

thank you very, very much !

(never I think this and automatic translate don't give this ...)

[dgiancaspro]

Sorry in advance for the long post ....
I completely understand the problem as it is stated. I wrote a quick brute force ruby program ... here it is ...

[snip]

I can't see what I'm doing wrong ... a nudge ... or a brick to the head ... in the right direction would be appreciated.

Thanks
Dave

[xan]

I can verify that your answer is correct. Please edit your post to remove the answer and code to avoid spoiling it for anyone else.

I don't know why your answer wasn't accepted. Maybe a copy/paste brought in some extra characters. If the problem persists, maybe an admin can figure out what the problem is.

[daniel.is.fischer]

Whether it was a copy/paste slip or a server glitch, please try again and if that doesn't work, notify us.

[dgiancaspro]

Looks like it was a Copy/Paste glitch ... The one thing I didn't try was typing it in by hand. That's what I get for being lazy.
Sorry for the spoiler .... I'll remember that in the future ...

Thanks
Dave

[hk]

Snipped out possible spoilers.
I don't think that makes for an efficient method: floats are slow compared to integers, moreover simple adding is much faster than multiplying or taking powers.
My prog based on the pdf runs in 0.003 milliseconds on a more than 4 years old computer using Delphi. (25 times as fast as yours)
Please do not post things like this again in the public part of this forum.

[chinesefishmarket]

I'm having trouble with getting an answer for #2.
I have tried it for smaller numbers (limit 55) and I get 44 (34 + 8 + 2) for the answer. When I enter 4000000 as my limit, I get the wrong answer. Is there something I am missing about this problem?

[ed_r]

Probably. Keep plugging away at it; you'll get there in the end. Good luck
_{(please note: this is not a hints forum!)}

[chinesefishmarket]

But if it works for a smaller number, it should work for a larger number as well.
I think the problem is my answers are coming out to be in the format X.XXXe+00X, because I tried problem 6 and it also said it was wrong.

So if my answer is 1.111e+003, the correct answer should be 1111 right?
(^ not an answer I got for either problem, just the same format).

[stijn263]

try using integers instead of floats/doubles.

what programming language do you use?

[chinesefishmarket]

try using integers instead of floats/doubles.

what programming language do you use?

C++

[chinesefishmarket]

try using integers instead of floats/doubles.

what programming language do you use?

C++

OK. Forcing everything to be int works out great.
Thank you.

[stijn263]

Yup, you should avoid using doubles unless you have a good reason for using them. All projecteuler problems have answers smaller than 2⁶³, so using long long int will be sufficient.

If you're using cout to output your numbers, you can change the precision of the double output by setting: cout.precision(15);

Ints will always be fully shown.

[phillyj]

Hi, I looked over a previous post on #2 but I'm still confused. In my understanding, am I to find:

[1] the sum of all the even numbers and the sum should be less than or equal to 4 million?

[2] the sum of the even numbers under each of which is less than or equal to 4 million? In this case, the answer can be greater than 4 million.

Which way am I supposed to solve it?

Thank you

[Susanne]

It is case [2]. Each of the numbers must be smaller or equal 4 million.

[phillyj]

I give up...for today. I thought I got the numbers but I keep getting it wrong. My code must be bad. I'm using matlab.