replace mathblog.dk links with waybackmachine
This commit is contained in:
parent
be1c44ffc6
commit
ba579dab23
@ -1 +1 @@
|
||||
Here I was desperately in need of an efficient algorithm. So I copied [this](http://www.mathblog.dk/triangle-number-with-more-than-500-divisors/) one from mathblog.dk and translated it into befunge. And I have to say it's amazingly fast.
|
||||
Here I was desperately in need of an efficient algorithm. So I copied [this](https://web.archive.org/web/20150314051848/http://www.mathblog.dk/triangle-number-with-more-than-500-divisors/) one from mathblog.dk and translated it into befunge. And I have to say it's amazingly fast.
|
@ -1,4 +1,4 @@
|
||||
This is effectively an optimized implementation of [this algorithm](http://www.mathblog.dk/project-euler-51-eight-prime-family/).
|
||||
This is effectively an optimized implementation of [this algorithm](https://web.archive.org/web/20150307042855/http://www.mathblog.dk/project-euler-51-eight-prime-family/).
|
||||
You can see the ten patterns on the left side and beside them the area were we build our numbers.
|
||||
|
||||
So what we do is iterate through the numbers from `100` to `1 000`, through the ten patterns and through the digits `0`, `1` and `2`.
|
||||
|
@ -1,4 +1,4 @@
|
||||
It's obvious that the bottleneck of this program is the primality test.
|
||||
The numbers become here too big to create a sieve and "normal" prime testing takes too long.
|
||||
So we use the [Miller-Rabin primality test](https://en.wikipedia.org/wiki/Miller-Rabin_primality_test) that I implemented a while ago (thank [mathblog.dk](http://www.mathblog.dk)).
|
||||
So we use the [Miller-Rabin primality test](https://en.wikipedia.org/wiki/Miller-Rabin_primality_test) that I implemented a while ago (thanks [mathblog.dk](https://web.archive.org/web/20150314052138/http://www.mathblog.dk/project-euler-58-primes-diagonals-spiral/)).
|
||||
The rest is just enumerating all the diagonals until `primes*10<all`
|
@ -2,12 +2,12 @@ Wow, so this is now officially my biggest (in terms of file size) befunge progra
|
||||
The file has around ten megabyte. And probably also in terms of unique variables (26 variables plus two 2D-arrays)
|
||||
|
||||
The problem was also not that *befunge-compatible*.
|
||||
My solution is pretty similar with the one from [MathBlog](http://www.mathblog.dk/project-euler-60-primes-concatenate/).
|
||||
My solution is pretty similar with the one from [MathBlog](https://web.archive.org/web/20150407005005/http://www.mathblog.dk/project-euler-60-primes-concatenate/).
|
||||
We generate primes from `1` to `3300` and save verified pairs in an Hashmap.
|
||||
And when I say Hashmap I mean an *fucking* `3000x3000` array where every possible pair has an field (yay for befunge).
|
||||
|
||||
I had to use quite a few codesnippets from older project:
|
||||
My standard [sieve of eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes), an implementation of the [Miller-Rabin primality test](https://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test) and method to [concatenate two numbers](http://www.mathblog.dk/files/euler/Problem60.cs).
|
||||
My standard [sieve of eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes), an implementation of the [Miller-Rabin primality test](https://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test) and method to [concatenate two numbers](https://web.archive.org/web/20150103211935/http://www.mathblog.dk/files/euler/Problem60.cs).
|
||||
|
||||
In the end is to say that in befunge the program size is normally an good indicator for the runtime (not really, but its kinda correct for all my programs).
|
||||
So as you probably guessed this program takes a pretty loooooong time to complete.
|
||||
|
@ -1,3 +1,3 @@
|
||||
I had a really complicated solution where I tried to generate an Phi Sieve and had to work around a lot of corner cases.
|
||||
Then I looked at [this](http://www.mathblog.dk/project-euler-69-find-the-value-of-n-%E2%89%A4-1000000-for-which-n%CF%86n-is-a-maximum/) solution and - well - it's faster and simpler than mine.
|
||||
Then I looked at [this](https://web.archive.org/web/20150326003453/http://www.mathblog.dk/project-euler-69-find-the-value-of-n-%E2%89%A4-1000000-for-which-n%CF%86n-is-a-maximum/) solution and - well - it's faster and simpler than mine.
|
||||
So I translated it to befunge.
|
@ -1,4 +1,4 @@
|
||||
The solution is practically identical to the one from [Mathblog](http://www.mathblog.dk/project-euler-70-investigate-values-of-n-for-which-%CF%86n-is-a-permutation-of-n/).
|
||||
The solution is practically identical to the one from [Mathblog](https://web.archive.org/web/20150326005645/http://www.mathblog.dk/project-euler-70-investigate-values-of-n-for-which-%CF%86n-is-a-permutation-of-n/).
|
||||
But Kristian explains it much better than I :).
|
||||
|
||||
We use our trustworthy [Sieve of Eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes) snippet and the *GetCombinatoricHash*-function from problem-62
|
||||
|
@ -1,4 +1,4 @@
|
||||
Again the algorithm is from [MathBlog](http://www.mathblog.dk/project-euler-78-coin-piles/).
|
||||
Again the algorithm is from [MathBlog](https://web.archive.org/web/20150326121651/http://www.mathblog.dk/project-euler-78-coin-piles/).
|
||||
I can't really say that I understand the algorithm fully (and the MathBlog guy says he neither).
|
||||
|
||||
But for the best explanation you better read his article.
|
@ -1,5 +1,5 @@
|
||||
Nothing much to say about this one, we play a bit with the triangle formulas until we reach something that looks like a [Pell equation](https://en.wikipedia.org/wiki/Pell%27s_equation).
|
||||
My approach is basically the same as the one on [mathblog.dk](http://www.mathblog.dk/project-euler-94-almost-equilateral-triangles/), but he explains it better.
|
||||
My approach is basically the same as the one on [mathblog.dk](https://web.archive.org/web/20150420081602/http://www.mathblog.dk/project-euler-94-almost-equilateral-triangles/), but he explains it better.
|
||||
(And I improved my approach a bit after I read his article, his math skills are pretty good :D).
|
||||
|
||||
The code is in a way interesting because it only has a single conditional operator.
|
||||
|
Loading…
x
Reference in New Issue
Block a user