[AccessD] miracle required apparently

[Paul Wolstenholme]

There is a similar problem at
https://www.rd.com/article/einsteins-riddle-solve-it/

I had a colleague who wrote code (probably in C or a derivative) that took
about a day to execute in 1999 and gave an answer.
I wrote an Access 95 query that took about a second to reveal the possible
variations that are encompassed in the ambiguities of the problem statement.

My technique was first to form a table of all the permutations (in this
case of 5 things, meaning 120 entries).
Next I formed a query for each thing that could lie in any of those
permutations.
Finally I formed a query that started as the cross product of each of those
queries but was linked according to the rules of the problem.
(After that I showed the final query's results in a form).

I expect my former colleague is still plotting his revenge.

Paul Wolstenholme

On Wed, 18 Oct 2023 at 08:14, Paul Hartland via AccessD <
accessd at databaseadvisors.com> wrote:

> I don't have much time until the weekend for knocking up a quick test, but
> think that scenario is pretty doable with 4 lots of times, 4 lots of
> classes, upto 8 participants and not being the same time or class zone more
> than once
>
> Paul
>
> On Tue, 17 Oct 2023, 02:22 Steve Schapel, <
> steve at datamanagementsolutions.biz>
> wrote:
>
> > Hi all
> >
> > I'm trying to do something that I initially thought would be reasonably
> > easy.  But alas, so far success has eluded me.  Any insights accepted
> > with much gratitude!
> >
> > The goal:  Assign a number of Participants to a number of Activities
> > over a number of Sessions.
> >
> > Very simple example:
> >      4 Sessions
> >      4 Activities
> >      8 Participants (therefore 2 per Activity)
> >
> > To illustrate:
> > Let's say the sessions are 9am, 10am, 11am, 12pm.
> > Let's sat the activities are chess, tai chi, bowls, diving
> > Let's say the participants are A, B, C, D, E, F, G, H
> >
> > The stipulation is that each participant should do each activity one
> > time.
> >
> > By trial and error brute force, I know that there is at least one
> > solution, namely:
> >
> >                       chess       tai chi       bowls        diving
> >    9am           A & E        C & F        D & G        B & H
> > 10am           C & G       A & H       B & E         D & F
> > 11am           D & H      B & G        A & F         C & E
> > 12pm           B & F       D & E        C & H        A & G
> >
> > HOWEVER, I have tried multiple angles of looping through nested (and
> > sometimes randomised) recordsets based on the core data elements
> > (sessions, activities, and participants), to write the assignments to
> > the available slots in a schedule table, and to my shock (and horror) we
> > always reach the point in the procedure where it gets stuck, due to
> > trying to assign a participant to two activities in the same session,
> > but with no valid alternative slot available.
> >
> > There is no problem if the model calls for the super simple option of
> > only one participant for each activity.  But otherwise, no dice, so far.
> >
> > There MUST be a way to make this work?  Surely?
> >
> > Thanks a lot.
> >
> > Regards
> > Steve
> > --
>
>