Question

Write a Python program that implements the Towers of Hanoi, using the recursive algorithm discussed in class.

Use command-line arguments to pass parameters to the program -

spring% python towersOfHanoi.py
USAGE: towersOfHanoi.py <# rings> <FROM peg> <TO peg>

spring% python towersOfHanoi.py  4 1 3
Move disk from peg 1 to peg 2
Move disk from peg 1 to peg 3
Move disk from peg 2 to peg 3

Move disk from peg 1 to peg 2
Move disk from peg 3 to peg 1
Move disk from peg 3 to peg 2
Move disk from peg 1 to peg 2
Move disk from peg 1 to peg 3
Move disk from peg 2 to peg 3
Move disk from peg 2 to peg 1
Move disk from peg 3 to peg 1

Answer 1

Code is as follows:

import sys #import sys for command line arguments

def TowerOfHanoi(n , from_peg, to_peg, aux_peg): #TowerOfHanoi function with n as no of disks from_peg(source),to_peg(destination),aux_peg(auxiliary)
if n == 1:
print("Move disk from peg",from_peg,"to peg",to_peg)
return
TowerOfHanoi(n-1, from_peg, aux_peg, to_peg) #recusrsive call to TowerOfHanoi
print("Move disk","from peg",from_peg,"to peg",to_peg)
TowerOfHanoi(n-1, aux_peg, to_peg, from_peg) #recusrsive call to TowerOfHanoi

pegs = [1,2,3] #pegs are 1,2 and 3
n = int(sys.argv[1]) #get n from command line argv 1
from_peg = int(sys.argv[2]) #get source from argv 2
to_peg = int(sys.argv[3]) #get destination from argv 3

pegs.remove(from_peg) #remove from_peg from pegs
pegs.remove(to_peg) #remove to_peg from pegs
aux_peg = pegs[0] #then take the remaiing peg as auxiliary peg
  

TowerOfHanoi(n,str(from_peg),str(to_peg),str(aux_peg)) #function call

************************************************************************************************************************************

Screesnhot of the code:

Output: