Euler Problems

Sat Jul 12 21:53:31 BST 2008

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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