Solved

The Tower of Hanoi problem

Posted on 1998-03-10
7
400 Views
Last Modified: 2013-12-26
I need to write a shell script on a Sun system in K-shell that solves the Tower of Hanoi Problem.  It must use a recursive function.  I'm stumped.  

Sorry, perhaps I should have elaborated.  I have a sample program written out for this problem.  I have the function already set up and it does call itself.  The problem lies in the fact that it doesn't move the disks in the right order.
0
Comment
Question by:KCMSzwak
7 Comments
 
LVL 3

Expert Comment

by:q2guo
ID: 1296111
most of the recursive function can be replaced by using loops.
0
 
LVL 32

Expert Comment

by:jhance
ID: 1296112
Sounds like a homework problem.  How about a hint?

The k-shell provides for function definitions.  So in your script you can define one like:

function blah
{
   # Do some stuff
}

So it follows that you can have blah call itself recursively:

function blah
{
  # Do some stuff
  blah

  # Do some more stuff
}

Don't forget that somewhere you have to test whether blah needs to be called again.  Otherwise, you'll just keep calling blah until the computer's memory runs out.
0
 

Author Comment

by:KCMSzwak
ID: 1296113
Edited text of question
0
Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

 
LVL 32

Expert Comment

by:jhance
ID: 1296114
Obviously you've programmed it wrong.  Program it correctly and it's likely to work.  From what you've posted, I don't see that any more definitive help is possible.
0
 
LVL 4

Expert Comment

by:jos010697
ID: 1296115
Show me your code and I'll try to fix it (I know next to nothing about the ksh, so
I need your syntax first ;-) In pseudo code:

# from, to == 1, 2, 3, size >= 0
function Hanoi(from, to, size) {

   if (size) {
      Hanoi(from, 6-from-to, size-1);
      move(from, to);
      Hanoi(6-from-to, to, size-1);
   }

kind regards,

Jos aka jos@and.nl

0
 

Expert Comment

by:dps96r
ID: 1296116
There are also a range of non-recursive solutions to the towers
of hanoi problem. A stack should not be too hard to improvise if
the syntsx is something close to a bourne shell--just use a stack
pointer (i.e. counter) and eval to get the right number of levels
of shell expansion. This probably leaves some values around but
unset fixes that if you want the fineese. [I would be unlikely to
bother myself].
0
 

Accepted Solution

by:
shivak earned 50 total points
ID: 1296117
#!/bin/ksh

# A recurssive function to perform the moves
hanoi()
{
    if [ $1 -ne 0 ]
    then
        hanoi `expr $1 - 1` $2 $4 $3
        echo "Move disk $1 from peg $2 to peg $3"
        hanoi `expr $1 - 1` $4 $3 $2
    fi
}


#main program
echo "Enter the number of disks :"
read x
if [ "$x" -ge 0 ]
then
    # Call hanoi to move N disks from peg A to peg C
    # using peg B
    hanoi $x A C B
else
    echo Its invalid
fi 2>/dev/null

0

Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Change owner from userA to server Local Administrators 7 66
while loop over for loop 7 115
Unix Command -- Challenging  question 7 96
unix example issues 18 100
In this article, I'll describe -- and show pictures of -- some of the significant additions that have been made available to programmers in the MFC Feature Pack for Visual C++ 2008.  These same feature are in the MFC libraries that come with Visual …
Introduction: Load and Save to file, Document-View interaction inside the SDI. Continuing from the second article about sudoku.   Open the project in visual studio. From the class view select CSudokuDoc and double click to open the header …
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …

821 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question