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-   -   The Project Euler thread (http://www.flashflashrevolution.com/vbz/showthread.php?t=120818)

leonid 10-25-2011 03:58 PM

Re: THE project euler thread
 
don't worry you are not alone

pmonibuv1 10-25-2011 05:08 PM

Re: THE project euler thread
 
I have 2 answered. Go me! \o/

XCV 10-25-2011 05:24 PM

Re: THE project euler thread
 
I saw this about a week ago and I'm up to 8 or 9...impressive right? xD

stargroup100 10-25-2011 05:25 PM

Re: THE project euler thread
 
dude rubix just use my conjectures

they're pretty much correct

here I'll even repost them again


1. A term in a maximal sum subset can never have more than two unique prime factors.
2. When optimizing the sum of a subset by choosing to multiply two powers of primes, the two primes are never both below sqrt(n).
3. For high values of n, no term in a maximal sum subset can be composed of only a single prime factor below sqrt(n) raised to a power, except for values close to sqrt(n).

iironiic 10-25-2011 05:36 PM

Re: THE project euler thread
 
I got #72 in about two seconds. Only took one line of coding in Mathematica haha. I'll look into the most recent problem when I have more time.

Reincarnate 10-25-2011 05:42 PM

Re: THE project euler thread
 
Quote:

Originally Posted by stargroup100 (Post 3557021)
dude rubix just use my conjectures

they're pretty much correct

here I'll even repost them again


1. A term in a maximal sum subset can never have more than two unique prime factors.
2. When optimizing the sum of a subset by choosing to multiply two powers of primes, the two primes are never both below sqrt(n).
3. For high values of n, no term in a maximal sum subset can be composed of only a single prime factor below sqrt(n) raised to a power, except for values close to sqrt(n).

I'm aware of all these -- it doesn't address the problem I'm having unfortunately

Reincarnate 10-25-2011 06:01 PM

Re: THE project euler thread
 
omfg



Unfortunately had to do some manual work (it COULD be automated but it just wasn't worth the headache)

stargroup100 10-25-2011 06:39 PM

Re: THE project euler thread
 
gj

right now I'm workin on uh, 351 I believe


the only roadblock I ran into is the fact that the summatory of the euler totient function is retardedly slow to calculate for very high values

if I can find an easy way to compute that then I have my answer

Reincarnate 10-25-2011 06:44 PM

Re: THE project euler thread
 
Actually SG the totient function is fine for that problem (that's what I used and I solved it earlier today) -- you just need a more efficient function

stargroup100 10-25-2011 06:48 PM

Re: THE project euler thread
 

for the summation of totient? really?

Reincarnate 10-25-2011 06:53 PM

Re: THE project euler thread
 
Quote:

Originally Posted by stargroup100 (Post 3557063)

for the summation of totient? really?

yes

stargroup100 10-25-2011 07:00 PM

Re: THE project euler thread
 
okay I made a small improvement on the speed of computation but it's not anything significant. what the hell did you do

Reincarnate 10-25-2011 07:22 PM

Re: THE project euler thread
 
Try messing around with http://pari.math.u-bordeaux.fr/

leonid 10-25-2011 07:22 PM

Re: THE project euler thread
 
yeeeeessssshhhhh


hondaracer600 10-25-2011 07:32 PM

Re: THE project euler thread
 
Reincarnate

I have been lurking on this thread for a few days. I wanted to see if I could pick your brain a bit on problem 355.

I have been getting close by implementing FFR4EVA_00's method of [a_2,a_3,a_5...a_p]. It is basically bumping the exponent of all primes < N

But alas, the answer is incorrect.

Did you use a method like this? Or did you go down a different path?

stargroup100 10-25-2011 07:44 PM

Re: THE project euler thread
 
You have to do a lot more with that because the method for checking optimization possibilities from there is much too broad and will take forever.

If you try to optimize that you'll be doing well over 10^(300+) calculations, which your program will not finish within the lifespan of the universe.

Reincarnate 10-25-2011 07:45 PM

Re: THE project euler thread
 
Quote:

Originally Posted by hondaracer600 (Post 3557084)
Reincarnate

I have been lurking on this thread for a few days. I wanted to see if I could pick your brain a bit on problem 355.

I have been getting close by implementing FFR4EVA_00's method of [a_2,a_3,a_5...a_p]. It is basically bumping the exponent of all primes < N

But alas, the answer is incorrect.

Did you use a method like this? Or did you go down a different path?


Raising the exponents of the initial "<N" prime list is just a starting point -- from there you need to create prime composites that you can add into the list. Just a matter of determining which composites are worth adding and which are useless. Some of them will be ambiguous -- which is what was tripping me up for the better part of 1.5 days. I ultimately had to do that part manually. I'm not sure if FFR4EVA had a fully automated solution or not, but mine wasn't.

stargroup100 10-25-2011 07:57 PM

Re: THE project euler thread
 
holy crap pari/gp lololol

this thing rules lololololololol

****in hell

hondaracer600 10-25-2011 08:11 PM

Re: THE project euler thread
 
Quote:

Originally Posted by Reincarnate (Post 3557093)

Raising the exponents of the initial "<N" prime list is just a starting point -- from there you need to create prime composites that you can add into the list. Just a matter of determining which composites are worth adding and which are useless. Some of them will be ambiguous -- which is what was tripping me up for the better part of 1.5 days. I ultimately had to do that part manually. I'm not sure if FFR4EVA had a fully automated solution or not, but mine wasn't.

Define "Manually". Are we talking pen and pad here?

stargroup100 10-25-2011 08:20 PM

Re: THE project euler thread
 
Yes, the four of us that solved it all did the last part manually.


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