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Project Euler
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Author:  Fogmeister [ Wed Mar 24, 2010 12:55 pm ]
Post subject:  Project Euler
Thought I'd create an branch from Fin's exam thread.

http://projecteuler.net/index.php?section=about

Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.

The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.

I've managed problem 1 and 5 so far as they're the only ones I've tried :D

I don't know if many people will do these from this forum but please post in spoiler colours (i.e. white) if you have the solution or provide hints etc...
Author:  Fogmeister [ Wed Mar 24, 2010 1:21 pm ]
Post subject:  Re: Project Euler
OK, done 2 and 6 now :D

Need to do some work now though.
Author:  Fogmeister [ Wed Mar 24, 2010 1:30 pm ]
Post subject:  Re: Project Euler
and now 8 :D

I need to do some of these in Java as the language I use at work isn't up to much number crunching.
Author:  finlay666 [ Wed Mar 24, 2010 2:00 pm ]
Post subject:  Re: Project Euler
I did one, I have a solution to 282 HOWEVER I need to change it from recursive to iterative as doing it recursively causes a stack overflow :D

I'd suggest doing one easy then one hard :)
Author:  Fogmeister [ Wed Mar 24, 2010 2:52 pm ]
Post subject:  Re: Project Euler
Yeah, after a few lines I realised that it would be possible to work out what the final value is fairly easily by viewing it as a whole rather than individual A(m,n) functions.

Will have a go tonight.

Will be interesting to compare code (although I'll be in Java or ObjC).
Author:  Fogmeister [ Wed Mar 24, 2010 3:49 pm ]
Post subject:  Re: Project Euler
OK, aiming for 282 and then 11 tonight.

11 is a bit less numbery but a bit more interesting :D
Author:  Fogmeister [ Wed Mar 24, 2010 6:39 pm ]
Post subject:  Re: Project Euler
finlay666 wrote:
I did one, I have a solution to 282 HOWEVER I need to change it from recursive to iterative as doing it recursively causes a stack overflow :D

I'd suggest doing one easy then one hard :)

LOL, well it ran for about 5 minutes and then crashed :D
Author:  Fogmeister [ Wed Mar 24, 2010 8:01 pm ]
Post subject:  Re: Project Euler
Well, I'm stuck.

I can't seem to work out how to get this to work :D

Hmm... I wonder if there is a way of storing results into an array and so enabling the algorithm to grab the results without having to run the same iterations over and over.
Author:  Fogmeister [ Wed Mar 24, 2010 8:26 pm ]
Post subject:  Re: Project Euler
Fogmeister wrote:
Well, I'm stuck.

I can't seem to work out how to get this to work :D

Hmm... I wonder if there is a way of storing results into an array and so enabling the algorithm to grab the results without having to run the same iterations over and over.

OK, this is good! Definitely a step forward! I can get the result from A(5,0) in around half a second now.
Author:  Fogmeister [ Wed Mar 24, 2010 9:03 pm ]
Post subject:  Re: Project Euler
Fogmeister wrote:
Fogmeister wrote:
Well, I'm stuck.

I can't seem to work out how to get this to work :D

Hmm... I wonder if there is a way of storing results into an array and so enabling the algorithm to grab the results without having to run the same iterations over and over.

OK, this is good! Definitely a step forward! I can get the result from A(5,0) in around half a second now.

OK, I can run up to A(5,0) or A(4,2) and it runs very quickly.

A(5,0) runs in 0.005 seconds.

However, if I try to increase any side of these then I get a bad access error.

:(
Author:  finlay666 [ Wed Mar 24, 2010 9:57 pm ]
Post subject:  Re: Project Euler
Fogmeister wrote:
OK, this is good! Definitely a step forward! I can get the result from A(5,0) in around half a second now.

OK, I can run up to A(5,0) or A(4,2) and it runs very quickly.

A(5,0) runs in 0.005 seconds.

However, if I try to increase any side of these then I get a bad access error.

:([/quote]

but it's i,i not i, j so 1,1 2,2 3,3 4,4 5,5 6,6 and 0,0
Author:  Fogmeister [ Wed Mar 24, 2010 9:58 pm ]
Post subject:  Re: Project Euler
finlay666 wrote:
Fogmeister wrote:
Fogmeister wrote:
OK, this is good! Definitely a step forward! I can get the result from A(5,0) in around half a second now.

OK, I can run up to A(5,0) or A(4,2) and it runs very quickly.

A(5,0) runs in 0.005 seconds.

However, if I try to increase any side of these then I get a bad access error.

:(


but it's i,i not i, j so 1,1 2,2 3,3 4,4 5,5 6,6 and 0,0

Yeah :(

I figured if I could reduce the number of iterations done it would stop it crashing out.

I can't work out how to do it any other way?

It's kind of like the Towers of Hanoi problem in a way. Each time you increase a number it does everything before it again or soemthing.

Fin, have you done this one yet?
Author:  finlay666 [ Thu Mar 25, 2010 12:22 am ]
Post subject:  Re: Project Euler
Fogmeister wrote:
Fin, have you done this one yet?


No, at my gf's atm as my main pc has VS2008 C++ installed and my laptop only has C# (C++ I can increase the call stack to 1gb or so ;))

It's not iteratively that causes the problem, it's the recursion that is the problem and a stack overflow exception as a result, I have thought of a solution that is more iterative but will give it a shot when I get home. (combination of for/while loops to achieve the result which *SHOULD* not give the error)

Did 4 today, so 1,2,6,8,9 and 16 so far

The latter challenges are the ranked ones too btw so they may be worth a look for a challenge

16 was a bit of a tricky one in C# due to the double refactoring to scientific notation automatically, got it in the end though :D
Author:  Fogmeister [ Thu Mar 25, 2010 9:01 am ]
Post subject:  Re: Project Euler
I got number 9 done this morning.
Author:  Fogmeister [ Thu Mar 25, 2010 10:41 am ]
Post subject:  Re: Project Euler
I gave up on 282 for now.

Having a go at problem 17 and I've got an answer but it tells me it's wrong :(

I've double and triple checked my program and I can't find anything wrong. I've even double checked against several random numbers and it's doing it correctly.

Not sure what to do now?
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