[chbot] Choc Fish Challenge #5

[Michael Field]

I've made a start.... this is flawed (at the end of step 2 we haven't 
definitively identified the bundles at the far end) but might inspire 
somebody. My guess is that you need to use uneven wire counts in each 
bundle you can glean more information....

But I'm pretty sure that the divide into three groups and wiring up two 
is the correct starting point...

Mike

_*First step*_
Separate the cables into 3 bundles of 40, short all cables in the bundle 
together Connect each end of the battery terminals to one bundle of 40 
(leaving one bundle unconnected).

*Walk to the other end.*

Connect light to a random wire, and try to get a circuit by connecting 
to each of the other wires. If nothing lights, try another wire.

When you get a light, you will then be able to move one jumper around to 
find which 39 other wires are also in that bundle. Do the same with the 
other terminal of the bulb.

You will then have three bundles of 40. One you will be know more about 
(it's not connected at the other end) but you won't know which bundle is 
connected to the positive terminal, and which is to the negative (oh for 
an LED or meter).

_*Second step *_
For each bundle of 40, divide it into two sets of 20, and jumper 
together. Jumper two bundles of 20 from one of those connected to one of 
the battery terminals together, jumper each bundle of 20 from the 
unconnected pair to a bundle of 20 that is connected to the battery.

*Walk back to the other end*

Use the bulb in series with the battery to separate the starting end 
into 6 bundles of 20.  you will also be able to work out which bundle 
was connected to which battery terminal, accurately identifying both 
ends of the bundle.

Label each cable.

_*Step 3**& 4*_
Deal out the cables again 3 or 4 from each bundle of 20, into new 
bundles of 40. Repeat. The above process, *walking another two trips*
This will allow you to divide the cables into 36 bundles of three or four.

_*Step 5 & 6*_
Deal out the cables again bundles of 3 or for , into new bundles of 40. 
Repeat. The above process, *walking another two trips*
This will allow you to identify individual cables.


On 4/09/2011 7:48 p.m., Synco Reynders wrote:
> As I was pulling through some wires today I remembered this classic challenge...
>
> A 120 wire cable has been laid firmly underground between two
> telephone exchanges located 1km apart.
> After the cable was laid it was discovered the individual wires are
> not labeled. There is no visual way of knowing which wire is which and
> thus connections at either end is not immediately possible.
> As trainee technician your boss has asked you to sort it out and
> identify / label the wires at both ends. You only have a battery and
> light bulb to test continuity and tape/pen for labeling the wires.
>
> What is the shortest distance in kilometers you will need to walk to
> correctly identify and label each wire?
>
>

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