Project Euler...
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Shah-Cuber
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Posted: Mon Jul 06, 2009 6:00 pm Post subject: Re: Project Euler... |
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5 days of struggling with #246 ... I hate geometry problems >_>
Just calculate a given point from the center of the ellipse ... 'nough said ... Used Wolfram Alpha for most of the calculations =P |
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bbi5291
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Posted: Tue Jul 07, 2009 5:30 pm Post subject: Re: Project Euler... |
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Instead of using Wolfram Alpha, why not download the engine it uses for its calculations - Wolfram Mathematica? http://***********
lol, the domain is censored, but the link still works |
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Dan
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Posted: Tue Jul 07, 2009 6:22 pm Post subject: Re: Project Euler... |
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bbi5291 @ 7th July 2009, 5:30 pm wrote:
lol, the domain is censored, but the link still works
Theres a reason for that, no links to warez. |
Computer Science Canada
Help with programming in C, C++, Java, PHP, Ruby, Turing, VB and more! |
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Shah-Cuber
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Posted: Tue Jul 14, 2009 6:53 pm Post subject: Re: Project Euler... |
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Finally level 6 ...
I have a headache right now, but it took me a week to solve #248, which is numbers for which Euler's totient function equals 13!, a lot of little details to deal with primes, ahhg! ... it was hardcoded ...
Well, at least I can rest now ...
They changed the problem a while back from 100,000 to 150,000 for the number to find.
... great ... i still have to finish Coresilience and Ambiguous Numbers, this is torture. I'll sleep now ... |
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A.J
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Posted: Tue Jul 14, 2009 10:52 pm Post subject: RE:Project Euler... |
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I am kind of bored now that there aren't any more PE questions to do....it has been about 2 weeks w/out PE..
so I am suggesting new questions to them
and I got addicted to SC....
(I am in a MathCamp at washington....it is soooooooo fun!) |
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matt271
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Posted: Thu Jul 16, 2009 12:20 am Post subject: Re: Project Euler... |
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to anybody who cares... i think i have the best solution to Problem 40
Quote: An irrational decimal fraction is created by concatenating the positive integers:
0.123456789101112131415161718192021...
It can be seen that the 12^(th) digit of the fractional part is 1.
If d_(n) represents the n^(th) digit of the fractional part, find the value of the following expression.
d_(1) ? d_(10) ? d_(100) ? d_(1000) ? d_(10000) ? d_(100000) ? d_(1000000)
my solution in c99 is: (i hope this hides for non-spoilers)
c: | #include <stdio.h>
#include <stdlib.h>
int a [] = {1, 10, 190, 2890, 38890, 488890, 5888890};
int b [] = {1, 10, 100, 1000, 10000, 100000, 1000000};
int getindex (int, int* );
int matt (int);
inline int digit (int, int);
int main (int argc, char** argv ) {
int i, p = 1;
for (i = 1; i < 1000001; i *= 10)
p *= matt (i );
printf("%i\n", p );
return (EXIT_SUCCESS );
}
int getindex (int x, int a []) {
int i;
for (i = 0; i < 7; ++i )
if (a [i ] > x )
break;
return --i;
}
int matt (int x ) {
int i = getindex (x, a );
x -= a [i ];
int q = x / (i + 1);
int r = x % (i + 1);
q += b [i ];
return digit (q, r );
}
inline int digit (int q, int r ) {
return q / b [getindex (q, b ) - r ] % 10;
} |
the c code itself is not that impressive, but the math i used i think is. i have (what i like to think is) a brilliant method to derive the numbers u see in array a[]
does anybody care? anybodys thoughts? i wanted to post this on the thing for it, but its locked for archive. |
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Cyril
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Posted: Thu Jul 16, 2009 2:00 am Post subject: RE:Project Euler... |
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Haha, I suppose naming a function after yourself is the best alternative to becoming famous enough as to have others do it for you. Anyways, nice, clean, morally justified solution- out of laziness, I just used an ostringstream and bashed it. |
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A.J
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Posted: Wed Jul 22, 2009 11:52 am Post subject: RE:Project Euler... |
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Very nice solution Matt.
I like the clean code (you don't see that very often nowadays). However, I do not believe that you have the best solution.
Your method is certainly a good method, but I think there's a better one. However, I might be mistaken.
Once again, I like the cleanliness in the code. |
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Cyril
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Posted: Thu Jul 23, 2009 11:09 am Post subject: RE:Project Euler... |
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http://www.research.att.com/~njas/sequences/A033307
Oh wow, there's a closed-form formula. But this is impractical, as there would be precision errors with computing the Lambert W-function. Interesting though. |
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Shah-Cuber
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Posted: Mon Apr 26, 2010 2:24 am Post subject: Re: Project Euler... |
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Weeeeee - It's 3 am
Renewing post after 9 months ...
Coming back for new problems & more headaches
Enjoy! |
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A.J
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Posted: Mon Apr 26, 2010 7:04 am Post subject: RE:Project Euler... |
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Well, the latest problem, p289, is giving me quite some trouble. However the latest few, < 289, were pretty easy. Maybe Project Euler wants < 50 people to have solved all the problems |
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