Hanoi Tower programming challenge...
Jim Hurley
jhurley0305 at sbcglobal.net
Thu Jul 19 23:42:46 EDT 2012
Bob,
Everybody finds these recursive algorithms hard, really hard, especially the Tower of Hanoi. Trouble is you can't start at the top.
Start recursion with the factorial function. The factorial of 9 is 9 * factorial(8) and so on. Therefore:
function Factorial n
if n = 1 then
return 1
else
return n * factorial(n-1)
end if
end factorial
And everybody finds fitting algorithms to physics problems hard. Again, you can't start at the top. Trust me, I spent my life teach students how to put the math into physics.
Part of the problem of programming for physics problems is the computer language.
For example, the algorithm to draw the path of a baseball is as simple as:
put 4 into vx --x component of the velocity of the turtle
put 5 into vy
put .1 into gravity
repeat until ycor() < 0
incXY vx,vy --increase the x coordinate by vx and the y coordinate by vy
subtract gravity from vy -- add the acceleration (the rate of change in the velocity) to vy
end repeat
This in Turtle Graphics. This is why I have been promoting TG for science students. It is geometrically oriented. The turtle is easier to talk to, and he is really good at solving differential equations--as in the problem of the baseball above..
More of this in:
go url "http://jamesphurley.com/RunRev/TurtleGraphics.livecode"
Me? I find programming for the internet hard, really hard. I started in the middle. Big mistake.
Jim
>
> Message: 25
> Date: Thu, 19 Jul 2012 16:37:03 -0700
> From: Bob Sneidar <bobs at twft.com>
> To: How to use LiveCode <use-livecode at lists.runrev.com>
> Subject: Re: Hanoi Tower programming challenge...
> Message-ID: <EE614A6A-5ABF-4AF7-AE22-CE88CCD9BA73 at twft.com>
> Content-Type: text/plain; charset=us-ascii
>
> I just read up on this. Honestly, if someone had asked me to come up with a programmatical solution to this physical problem, I could not do it to save my life. I don't know why. I consider myself to be fairly intelligent, but I cannot turn physical problems like this into a formula.
>
> I stumbled at this on a lot of tests in school. Whenever it got to these kinds of problems I would stop dead in my tracks, even when the teacher said to skip over the problems we could not solve. I tried to work out the relationships of the physical problem to the mathemetical expression of it and I could not go on until I "saw" in my head how it all worked and why.
>
> I could probably get through the physical puzzle fine and "see" why it had to work that way, but to convert it to a formula is quite beyond me. <sigh> Very frustrating. This is probably why I could never be a very good developer, at least when it comes to this sort of thing.
>
> Bob
>
>
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