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Merged
merged 7 commits into from
Apr 8, 2023
Merged

Queue implementation using two Stacks #8617

merged 7 commits into from
Apr 8, 2023

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amirsoroush
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Queue using two Stacks:

LQJBQ

Here is the implementation of Queue using two stacks. It has O(1) time complexity for en-queuing and Amortized O(1) for de-queuing. The worst case time complexity for de-queuing is O(n) though. The rationale behind this and its use-cases are mentioned here and here.

I also included doctest for methods. It's formatted using "Black" and checked by "Mypy".

  • 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 include at least one URL that points to Wikipedia or another similar explanation.
  • If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

@algorithms-keeper algorithms-keeper bot added the awaiting reviews This PR is ready to be reviewed label Apr 7, 2023
@algorithms-keeper algorithms-keeper bot added the tests are failing Do not merge until tests pass label Apr 7, 2023
@amirsoroush
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Apparently ruff is not happy with my commit. It says:

Error: computer_vision/lenet_pytorch.py:9:8: PLR0402 Use `from torch import nn` in lieu of alias
Error: Process completed with exit code 1.

Unfortunately I have no idea about it. I didn't import anything from torch.

@CaedenPH
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CaedenPH commented Apr 7, 2023

Apparently ruff is not happy with my commit. It says:

Error: computer_vision/lenet_pytorch.py:9:8: PLR0402 Use `from torch import nn` in lieu of alias
Error: Process completed with exit code 1.

Unfortunately I have no idea about it. I didn't import anything from torch.

Seems like you didn't touch that file so someone must've merged a commit that failed ruff

@amirsoroush
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@CaedenPH I guess the failure is because of the merged commit which is currently requested to be reverted here.

cclauss
cclauss requested changes Apr 8, 2023
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@algorithms-keeper algorithms-keeper bot added awaiting changes A maintainer has requested changes to this PR and removed awaiting reviews This PR is ready to be reviewed labels Apr 8, 2023
@algorithms-keeper algorithms-keeper bot added awaiting reviews This PR is ready to be reviewed and removed awaiting changes A maintainer has requested changes to this PR labels Apr 8, 2023
@algorithms-keeper algorithms-keeper bot removed the tests are failing Do not merge until tests pass label Apr 8, 2023
@cclauss
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cclauss commented Apr 8, 2023

For readability, please move the "magic" functions like .__len__() and .str()before.get()and.put()`

@amirsoroush amirsoroush requested a review from cclauss April 8, 2023 09:20
cclauss
cclauss approved these changes Apr 8, 2023
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LGTM

A few changes:

  • If you can use something immediately without naming it then do so to keep doctests short
  • Test the result, not the result == expected is True
  • Use repr() instead of str() in tests unless essential.
  • Favor tuples over lists when possible because they take less RAM.
  • We do not need a .size()` method if we have defined len.
  • The filename should match the class that is inside it.

@algorithms-keeper algorithms-keeper bot removed the awaiting reviews This PR is ready to be reviewed label Apr 8, 2023
@cclauss cclauss merged commit 5cb0a00 into TheAlgorithms:master Apr 8, 2023
@amirsoroush
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@cclauss Thank you for your advice and also for introducing me to ruff linter.

For .size(), "result == expected is True", "implementing __str__", I wanna say that I wrote them because they've been implemented in other files. I tried to be consistent with those but I'm totally agree with you. I'll also fix those in the future.

@amirsoroush amirsoroush deleted the Queue_with_two_stacks branch April 8, 2023 14:04
@cclauss
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cclauss commented Apr 8, 2023

Thanks for your contribution. Our codebase is not (yet) perfect so please submit pull requests for any existing algorithms that can be improved.

tianyizheng02 pushed a commit to tianyizheng02/Python that referenced this pull request May 29, 2023
@amirsoroush @cclauss @tianyizheng02
Queue implementation using two Stacks (TheAlgorithms#8617)
9609b48 
* Queue implementation using two Stacks

* fix typo in queue/queue_on_two_stacks.py

* add 'iterable' to queue_on_two_stacks initializer

* make queue_on_two_stacks.py generic class

* fix ruff-UP007 in queue_on_two_stacks.py

* enhance readability in queue_on_two_stacks.py

* Create queue_by_two_stacks.py

---------

Co-authored-by: Christian Clauss <[email protected]>
sedatguzelsemme pushed a commit to sedatguzelsemme/Python that referenced this pull request Sep 15, 2024
@amirsoroush @cclauss @sedatguzelsemme
Queue implementation using two Stacks (TheAlgorithms#8617)
eee9556 
* Queue implementation using two Stacks

* fix typo in queue/queue_on_two_stacks.py

* add 'iterable' to queue_on_two_stacks initializer

* make queue_on_two_stacks.py generic class

* fix ruff-UP007 in queue_on_two_stacks.py

* enhance readability in queue_on_two_stacks.py

* Create queue_by_two_stacks.py

---------

Co-authored-by: Christian Clauss <[email protected]>
@isidroas isidroas mentioned this pull request Jan 25, 2025
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3 participants
@amirsoroush @CaedenPH @cclauss