Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 24

Tell us what’s happening:

NUMBER_OF_DISKS = 3
number_of_moves = 2**NUMBER_OF_DISKS - 1
rods = {
‘A’: list(range(NUMBER_OF_DISKS, 0, -1)),
‘B’: ,
‘C’:
}

def move(n, source, auxiliary, target):
# display starting configuration
print(rods)
for i in range(number_of_moves):
remainder = (i + 1) % 3
if remainder == 1:
print(f’Move {i + 1} allowed between {source} and {target}')
forward = False
if not rods[target]:
forward = True

``````NUMBER_OF_DISKS = 3
number_of_moves = 2**NUMBER_OF_DISKS - 1
rods = {
'A': list(range(NUMBER_OF_DISKS, 0, -1)),
'B': [],
'C': []
}

def move(n, source, auxiliary, target):
# display starting configuration
print(rods)
for i in range(number_of_moves):
remainder = (i + 1) % 3
if remainder == 1:
print(f'Move {i + 1} allowed between {source} and {target}')
forward = False

# User Editable Region

if not rods[target]:
forward = True
elif not rods[source] and rods[source][-1] < rods[target][-1]:
forward = True

# User Editable Region

elif remainder == 2:
print(f'Move {i + 1} allowed between {source} and {auxiliary}')
elif remainder == 0:
print(f'Move {i + 1} allowed between {auxiliary} and {target}')

# initiate call from source A to target C with auxiliary B
move(NUMBER_OF_DISKS, 'A', 'B', 'C')
``````

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Challenge Information:

Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 24

1 Like

Which problem:
I’m on the “Learn Recursion by Solving the Tower of Hanoi Puzzle” problem in the Scientific Computing with Python certification and am stuck on stage 24 of this.

Problem:
This is the current code I have (above).

The elif statement I’ve added into is this:
elif not rods[source] and rods[source][-1] < rods[target][-1]:
forward = True

And the error message this is producing in the UI for the course is this:
" Sorry, your code does not pass. You’re getting there.

You should have an `elif` statement to check if `rods[source]` is not empty and `rods[source][-1] < rods[target][-1]`."

I’m not sure why this one isn’t working.

Try removing the `not` in front of `rods`

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