add binary_tree_traversals.py to data_structures

[rajansh87]

I have added some interesting binary tree traversing methods.

Describe your change:

In data_structures/binary_tree repository I have added a new file that includes some interesting methods for traversing a binary tree.

• 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}.

[rajansh87]

Can anyone help me out with what's the problem with my PR?

[cclauss]

Run your code thru psf/black as discussed in CONTRIBUTING.md

[rajansh87]

Any suggestions?

[cclauss]

This will save you a ton of manual formatting...

python3 -m pip install black
black data_structures/binary_tree/binary_tree_traversals.py

[rajansh87]

ok i'll try

[rajansh87]

?

[cclauss]

data_structures/binary_tree/binary_tree_traversals.py:24:89: E501 line too long (89 > 88 characters)
data_structures/binary_tree/binary_tree_traversals.py:34:89: E501 line too long (91 > 88 characters)

[rajansh87]

can you explain?

[cclauss]

Lines are not allowed to be longer than 88 characters max. Lines 24 and 34 are too long and must be wrapped.

[TravisBuddy]

Travis tests have failed

Hey @rajansh87,
Please read the following log in order to understand the failure reason.
It'll be awesome if you fix what's wrong and commit the changes.

TravisBuddy Request Identifier: 6838e980-0e68-11eb-964d-5d54b4986782

[TravisBuddy]

Travis tests have failed

Hey @rajansh87,
Please read the following log in order to understand the failure reason.
It'll be awesome if you fix what's wrong and commit the changes.

TravisBuddy Request Identifier: ade5d380-0e68-11eb-964d-5d54b4986782

[rajansh87]

I think we should not make further changes as it might becomeworse...

[cclauss]

Please do not give up... We are really close. Our testing now accepts trailing spaces inside triple quotes so your doctests should now work if your answers have one trailing space.

[rajansh87]

ok

[rajansh87]

what to do next?

[rajansh87]

why is this failing to build, can we see whats are the logs or what is error?

[cclauss]

• https://travis-ci.com/github/TheAlgorithms/Python/jobs/400069552#L467
• https://travis-ci.com/github/TheAlgorithms/Python/jobs/400069552#L772

[cclauss]

I hope this will be 100% green with doctests and type hints so we can land this PR.

Now I remember why I said that algorithmic functions should not print()... It makes testing too hard.

[rajansh87]

Yeah, Now i understood.

[TravisBuddy]

Travis tests have failed

Hey @rajansh87,
Please read the following log in order to understand the failure reason.
It'll be awesome if you fix what's wrong and commit the changes.

TravisBuddy Request Identifier: 76c03820-0ecf-11eb-9bff-abeacd856cb9

[rajansh87]

?

[dhruvmanila]

I think our entire repository is based on the code style of black. We should fix the file instead of ignoring it in black.

[cclauss]

I will revert the black change in a separate PR.

[dhruvmanila]

Black is actually not changing the file in the current state.

$ black --check binary_tree_traversals.py
All done! ✨ 🍰 ✨
1 file would be left unchanged.

[cclauss]

Yes, See #3318

[rajansh87]

thanks, guys it was really very interesting and helpful of you because this was my first time when I was contributing to such a huge repo. Learned a lot of kinds of stuff which I had not any idea. Thanks, @cclauss, and @dhruvmanila for helping me troughout.

[cclauss]

This was work well done. Please come back with another algoritym soon.

There are still doctests missing from many of those functions if you can figure out how to add them.

[rajansh87]

yeah, i was looking at that only. Any suggestions!

[cclauss]

Perhaps yield node.data as you traverse the tree and then print(", ".join(my_yielding_function(root)))

Using yield is always a bit of a mind-bender.