Euler Problems

Andrew Mathenge mathenge at gmail.com
Sun Jul 13 00:16:25 BST 2008 

I switched to C/C++ when I realised that perl was going to make me
grey before anything came out.

I might do what you did with #18 but right now I have a pad full of
numbers, notes, lines and many other scribbles. I'm looking for some
sort of logic. If I don't have an "eureka" moment, then I'll create
that multi-dimensional array and brute force my way through it.

Alternatively, I can do it manually, but that will make me feel less of a man.

Andrew.

On Sat, Jul 12, 2008 at 4:53 PM, kinuthiA muchanE <muchanek at gmail.com> wrote:
> Habari,
> ... and what language are you using Mathenge? Perl? #18 proved to be too
> demanding for me, actually I skipped it all together with #15, I only
> solved them yesterday!! The best way, IMHO, to solve #18 is to have a
> multi-dimensional array, or in Python a list of lists, and then realise
> that you are either at the end or at the beginning of the array...Oh
> my... that sounds obscure!
> :-/
> Kinuthia...
> On Sat, 2008-07-12 at 15:13 -0400, Andrew Mathenge wrote:
>> Until you posed question #26 I didn't even know project euler existed
>> Bwana Kinuthia, but I'm trying my best.
>>
>> Right now #18 is killing me trying to solve it without brute force.
>> And I agree. Zacharia did a great job with #12. Mine took forever.
>>
>> Zacharia, sign up.
>>
>> The dance continues....
>>
>> On Sat, Jul 12, 2008 at 1:15 PM, kinuthiA muchanE <muchanek at gmail.com> wrote:
>> > Habari wote,
>> >
>> > Now, this is getting lively, and I think Zacharia is the teacher all of
>> > us have been longing for :-) Step by step, you elucidate all the
>> > underling principles. I thought nobody ever reads this, I am mistaken.
>> > Zacharia, why dont you subscribe to project Euler
>> > (http://projecteuler.net ) and at least I will not be leading in the
>> > list Kenyans who have solved the most problems, only 52, the last time I
>> > looked.
>> > And to Andrew (ha... you are at 17 ),  you ask a question and then
>> > disappear!! Hmmmm, and where is Miano??
>> >
>> > Cheers!!
>> > Kinuthia...
>> >
>> >
>> >
>> > On Sat, 2008-07-12 at 07:16 -0700, Zacharia M. Rugongo wrote:
>> >> This email is from a ubuntu-ke subscriber to other subscribers inluding you:)
>> >> My solution to Euler #12 runs in less than 1 minute.
>> >>
>> >>
>> >> Let us list the factors of the first eight triangle numbers:
>> >>  1: 1
>> >>  3: 1,3
>> >>  6: 1,2,3,6
>> >> 10: 1,2,5,10
>> >> 15: 1,3,5,15
>> >> 21: 1,3,7,21
>> >> 28: 1,2,4,7,14,28
>> >> 36: 1,2,3,4,6,8,9,12,18,36
>> >> Note the numbers that are underlined in each sequence. This is the half way point.
>> >> a)  If you divide the triangle number by the first number that is underlined the result will be greater than the divisor.
>> >> b)
>> >> On the other hand if you divide the triangle number by the second
>> >> number that is underlined the result will be less than the divisor.
>> >> c)
>> >> The triangle number 36 has only one number at the centre of the
>> >> sequence, because that centre number is the square root of the triangle
>> >> number 36.
>> >>
>> >> In
>> >> cases a) and b) if you wanted to know the total number of divisors, you
>> >> look for the position of the number underlined as described in b), then
>> >> subtract 1 from it, then multiply it by 2. For example, for triangle
>> >> number 28, value 7 is in position 4. So (4-1) * 2 = 6
>> >>
>> >> In
>> >> cases c) if you wanted to know the total number of divisors, you look
>> >> for the position of the center number underlined, then multiply it by
>> >> 2. For example, for triangle number 36, value 6 is in position 5.
>> >> So 5 * 2 = 10
>> >>
>> >> Here is the program.
>> >>
>> >>
>> >> Dim triagNo As Integer              ' Triangle number
>> >> Dim counter As Integer              ' for calculating the next triangle number
>> >> Dim varValue As Integer            ' Incremented in search for a Divisor
>> >> Dim NoDivisors As Integer        ' number of Divisors found
>> >> Dim Divisor As Integer              ' Value of found Divisor
>> >>
>> >> Do
>> >>    counter += 1
>> >>    triagNo = triagNo + counter
>> >>    varValue = 0
>> >>    Divisor = 0
>> >>    NoDivisors = 0
>> >>
>> >>       Do
>> >>          varValue += 1
>> >>          If triagNo Mod varValue = 0 Then                    ' is varValue a Divisor
>> >>          Divisor = varValue
>> >>          NoDivisors += 1
>> >>         End If
>> >>      Loop Until (triagNo / Divisor) <= Divisor               ' Find when you reach the second centre value
>> >>
>> >>      If (triagNo / Divisor) = Divisor Then
>> >>         NoDivisors = (NoDivisors - 1) * 2 + 1                  ' cases a) and b)
>> >>     Else
>> >>         NoDivisors = (NoDivisors - 1) * 2                        ' case c)
>> >>     End If
>> >>
>> >> Loop Until (NoDivisors > 500)
>> >>
>> >> TextBox1.Text = triagNo
>> >>
>> >>
>> >> Z. Mwangi
>> >>
>> >>
>> >>
>> >> ----- Original Message ----
>> >> From: Andrew Mathenge <mathenge at gmail.com>
>> >> To: ubuntu Kenya <ubuntu-ke at lists.ubuntu.com>
>> >> Sent: Friday, July 11, 2008 3:24:23 AM
>> >> Subject: Re: Euler Problems
>> >>
>> >> This email is from a ubuntu-ke subscriber to other subscribers inluding you:)
>> >> I've been working on #12 and the performance is simply not acceptable.
>> >> Has anyone been able to get this running as fast as some of the posts
>> >> on the site claim?
>> >>
>> >> Andrew.
>> >>
>> >> On Tue, Jul 8, 2008 at 12:40 PM, kinuthiA muchanE <muchanek at gmail.com> wrote:
>> >> > Andrew,
>> >> > For #10, if you do not use a sieve to find the primes, it will run
>> >> > forever!
>> >> > There is one called the Sieve of Erastothenes. Check it out on
>> >> > Wikipedia.
>> >> >
>> >> > Good luck :-)
>> >> > Kinuthia...
>> >> > On Tue, 2008-07-08 at 10:47 -0400, Andrew Mathenge wrote:
>> >> >> I'm still trying them. I started at #1 after the one you proposed
>> >> >> (#26) and I'm at #10 now. This one should be very simple but I don't
>> >> >> know why it's taking so long to run.
>> >> >>
>> >> >> Andrew.
>> >> >>
>> >> >> On Tue, Jul 8, 2008 at 6:52 AM, kinuthiA muchanE <muchanek at gmail.com> wrote:
>> >> >> > Habari,
>> >> >> > Anybody still trying these problems, you are all so, so silent...
>> >> >> >
>> >> >> > Kinuthia...
>> >> >> >
>> >> >> >
>> >> >
>> >> >
>> >>
>> >> --
>> >> Ubuntu-ke mailing list
>> >> Ubuntu-ke at lists.ubuntu.com
>> >> https://lists.ubuntu.com/mailman/listinfo/ubuntu-ke
>> >>
>> >>
>> >>
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