feat: Binary tree node sum (#7020)

[CaedenPH]

Describe your change:

Implements #7020
Algorithm to get the sum of all tree nodes

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[CaedenPH]

@cclauss pinging for review

[cclauss]

Let me know if you want to try the extra credit bit or not.

[cclauss]

from collections.abc import Iterator

Extra credit: def __iter__(self) -> Iterator[int]

• https://docs.python.org/3/reference/datamodel.html#object.__iter__
• https://github.com/TheAlgorithms/Python/search?q=__iter__

Then you could replace node_sum() with sum(binary_tree_node_sum).

[CaedenPH]

@cclauss
Is this what you meant?

[dhruvmanila]

Is this what you meant?

No, that's not what he meant. He's asking you to implement the iteration protocol for a custom Python object. It comprises of two methods __iter__ to which returns an iterator and __next__ which returns the next object.

These methods would be made available to the Node class which then would allow us to do:

sum(node.value for node in tree)

If you need a bit more understanding, I could help you out with an example.

A class for doing a sum seems redundant. Alternatively, you could just create a function instead.

[cclauss]

list(binary_tree_node_sum) would return [10, 5, 12, -3, 8, 0]

sum(binary_tree_node_sum) would return 32.

max(), min(), mean() would all just work out-of-the-box.

I would just define __iter__ and not define __next__ but whatever works for you. I would use yield more than return. There are lots of examples in this repo that I linked to above.

[CaedenPH]

list(binary_tree_node_sum) would return [10, 5, 12, -3, 8, 0]

sum(binary_tree_node_sum) would return 32.

max(), min(), mean() would all just work out-of-the-box.

I would just define __iter__ and not define __next__ but whatever works for you. I would use yield more than return. There are lots of examples in this repo that I linked to above.

Okay, I understand. However, perhaps all of this should be implemented in the basic binary tree or some other more general file instead of binary tree path sum