Confusing Algorithm

[Chris Angelico]

On Mon, Apr 22, 2013 at 10:39 PM, RBotha <r at ymond.co.za> wrote:
> I'm facing the following problem:
>
> """
> In a city of towerblocks, Spiderman can
> “cover” all the towers by connecting the
> first tower with a spider-thread to the top
> of a later tower and then to a next tower
> and then to yet another tower until he
> reaches the end of the city. Threads are
> straight lines and cannot intersect towers.
> Your task is to write a program that finds
> the minimal number of threads to cover all
> the towers. The list of towers is given as a
> list of single digits indicating their height.
>
> -Example:
> List of towers: 1 5 3 7 2 5 2
> Output: 4
> """
>
> I'm not sure how a 'towerblock' could be defined. How square does a shape have to be to qualify as a towerblock? Any help on solving this problem?

First start by clarifying the problem. My reading of this is that
Spiderman iterates over the towers, connecting his thread from one to
the next, but only so long as the towers get shorter:

First thread
1
New thread
5-3
New thread
7-2
New thread
5-2

There are other possible readings of the problem. Once you fully
understand the problem, write it out in pseudo-code - something like
this:

Iterate over towers sequentially
    If next tower is taller than current tower, new thread
Report number of new threads

And then turn it into code, and start running it and playing with
it... and debugging it. (There's a small error in the pseudo-code I
just posted; can you spot it?) Once you're at that point, if you get
stuck, post your code and we can try to help.

But fundamentally, I think you don't _need_ to define a towerblock. :)

ChrisA