Learn Recursion by Solving the Tower of Hanoi Puzzle - Step 27

Python
1

Tell us what’s happening:

Not sure if my statement that moves the pieces is wrong or not. I just switched target and source in the previous adjusting line of code.

Your code so far

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
            elif rods[source] and rods[source][-1] < rods[target][-1]:
                forward = True

# User Editable Region

            if forward:
                print(f'Moving disk {rods[source][-1]} from {source} to {target}')
                rods[target].append(rods[source].pop())
            else:
                print(f'Moving disk{rods[-1]} from {target} to {source}')
                rods[source].append(rods[target].pop())

# 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 27

2

Very close, but if you look again you didn’t quite mirror the statements.

print(f'Moving disk {rods[source][-1]} from {source} to {target}')
print(f'Moving disk{rods[-1]} from {target} to {source}')
3

I am still unsure what I am doing wrong.

4

If you are just reversing source and target, those two lines should be the same length, right?

5 
else: 
                print(f'Moving disk {rods[source][-1]} from {target} to {source}')
                rods[source].append(rods[target].pop())
6

Do you get an error or hint when you try this?

7

I’ve edited your code for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.

Pre-formatted-text
Pre-formatted-text1356×380 401 KB

See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (').

1 Like
8

I am getting an error message.

9

What is the error message?

10

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