[chbot] Choc Fish Challenge #5

[Synco Reynders]

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?