LabVIEW 2009 Recursive Programming CHALLENGE!

[Evan R.]

All,

As of LabVIEW 2009, we have strong recursion supported. I'm challenging any LabVIEW developers out there to program a LabVIEW version of the Towers of Hanoi.

This is an old puzzle developed by a mathematician in the 1800s. It also happens to be a problem which can be solved quite elegantly using recursion, and serves as the quintessential programming assignment when the concept of recursion is introduced in undergraduate CS / engineering programs!

The game: The Tower of Hanoi or Towers of Hanoi (also known as The Towers of Brahma) is a mathematical game or puzzle. It consists of three rods, and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks neatly stacked in order of size on one rod, the smallest at the top, thus making a conical shape. The objective of the puzzle is to move the entire stack to another rod, obeying the following rules:

• Only one plate may be moved at a time.
• Each move consists of taking the upper plate from one of the rods and sliding it onto another tower
• No plate may be placed on top of a smaller plate. [Source: Wikipedia].

The challenge is for you to write a LabVIEW program that will solve the Towers using recursion, and without hard coding the number of plates (the number of Towers are fixed at 3).

Here's a pictoral description of the game with 3 plates, but your solution should be able handle N plates. It took me 1 hour to write the LabVIEW code to do this, given the recursive pseudocode found through a google search.

Here is a screen capture of the front panel of the solution.

If you decide to give this programming challenge a try, and you'd like to take a look at my solution, either check back here in a few weeks, or send me an email and I'll forward you the code. You must have LabVIEW 2009 in order to complete this challenge! You can download a free evaluation here: http://www.ni.com/trylabview/

Finally, I've attached the front panel of the VI shown above for you to get started!

GOOD LUCK!

Evan

[Evan R.]

Any takers?

I clearly need to up the ante. The first person to respond will receive a classic vintage NI Week 2007 Laptop Side Satchel.

It's a really sweet prize, and it's limited edition. In fact only 4 bags were ever alloted to the WPA area.

Hurry and claim your prize!

(Actual bag may vary)

(Actually, this is a completely different bag I just found on google images, but YOUR bag will be pretty cool also)

[Frabto]

Hi,

After a little struggle I have done it in LabVIEW 8.6.1 using LVOOP(recursion) as I dont have LV 2009 now.

Thanks,

Niju

[MikeS81]

This is my 8.5 solution.

Mike

[MikeS81]

And now in LabVIEW 2009, as postulated.

Mike

[Evan R.]

Very cool solution.

I guess this serves as an excellent demonstration of capabilities of LabVIEW even before LV 2009. Recursive programming was an option in a few ways previously, as evidenced by these posts:

1. Through OOP

2. Through VI Server

Please send me an email with your contact information so I can send you your prize. Are you located in the Pittsburgh area? It's also possible for me to stop by your office if you're close by.

[Evan R.]

Mike,

Great answers too! And just a few hours later than the first response. You both win! I'll send you a prize as well if you contact me through email (evan.robinson@ni.com) with your contact information and shipping address.

Finally, I've posted my solution to this problem which is nearly identical to yours.

Congratulations, and the contest is now closed!

Best,

Evan