* create monoalphabetic cipher

* update file

* update file

* update file

* update file

* update file

* update after testing flake8 on this code

* update file

* update file

* update file

* update file

* update file

* update file

* create beaufort cipher

if you like my code, merge it and add the label as `hacktoberfest-accepted`

* update the file

* Update beaufort_cipher.py

* Update beaufort_cipher.py

* update as per black formatter

* Update beaufort_cipher.py

* update the file

* update file

* update file

* update file

* update file

* Fix the build -- 88 chars per line max.

* updating DIRECTORY.md
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* Fixed typo in caesar_cipher.py

* Typo fixes

* Qiskit: Add Quantum Half Adder

* fixup! Format Python code with psf/black push
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

With this set, Windows users will have text files converted from Windows style line endings (\r\n) to Unix style line endings (\n) when they’re added to the repository.
https://www.edwardthomson.com/blog/git_for_windows_line_endings.html

* Add GitHub action for Project Euler only

* Add second job for Project Euler

* Remove Project Euler jobs from Travis CI

* Fix typo for actions/setup-python

* Rename the workflow file

* Change name of file in workflow

* Remove comments from Travis config file

* Create evaluate_postfix_notations.py

Adding in the evaluate postfix notation using Stacks
one of the common use with simple stack question
creating a new file for the data structure of stacks

* Create evaluate_postfix_notations.py

Adding in the evaluate postfix notation using Stacks
one of the common use with simple stack question
creating a new file for the data structure of stacks

* Delete evaluate_postfix_notations.py

* Evaluate postfix expression stack clean approach

Sending in the PR again as the Previous request failed in pre commit

* Update evaluate_postfix_notations.py

* Update evaluate_postfix_notations.py

Made changes as per the required for fixing the failing pre-commits.

* Update evaluate_postfix_notations.py

Made changes as suggested by @cclauss

* Update evaluate_postfix_notations.py

fixed pre-commit fails

* Update evaluate_postfix_notations.py

fixing pre-commit fails

* Update evaluate_postfix_notations.py

Deleted trailing white spaces causing pre-commits to fail

* Update data_structures/stacks/evaluate_postfix_notations.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update data_structures/stacks/evaluate_postfix_notations.py
Co-authored-by: NChristian Clauss <cclauss@me.com>
Co-authored-by: NChristian Clauss <cclauss@me.com>

* include solution for problem 57

* fix line to long errors

* update filenames and code to comply with new regulations

* more descriptive local variables

* Create meanthresholding.py

* Rename meanthresholding.py to meanthreshold.py

* Update meanthreshold.py

* Update computer_vision/meanthreshold.py

Verified this part works, thanks.
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update computer_vision/meanthreshold.py
Co-authored-by: NChristian Clauss <cclauss@me.com>
Co-authored-by: NChristian Clauss <cclauss@me.com>

https://github.com/TheAlgorithms/Python/pull/2573 
the second implementation of the Doubly linked list

* Added solution for Project Euler problem 75. 

* Added doctest for solution() in project_euler/problem_75/sol1.py

* Update docstring and 0-padding of directory name. Reference: #3256

* More descriptive variable names

* Moved solution explanation to module-level docstring

* Added solution for Project Euler problem 91. Reference: #2695

* Added doctest for solution() in project_euler/problem_91/sol1.py

* Update docstring and 0-padding in directory name. Reference: #3256

* Update sol1.py
Co-authored-by: NDhruv <dhruvmanila@gmail.com>

* Added solution for Project Euler problem 174. 

* Fixed import order and removed executable permission from sol1.py

* Update docstrings, doctests, and annotations. Reference: #3256

* Update docstring

* Update sol1.py
Co-authored-by: NDhruv <dhruvmanila@gmail.com>

* Added solution for Project Euler problem 72.

* Update type annotations and 0-padding of the directory name. Reference: #3256

* Rename sol1.py to sol2.py

* Added newline at the end of sol2.py

* Revert sol1.py

* updating DIRECTORY.md

* updating DIRECTORY.md

* Fixed accidental commit of file I have't touched

* fixup! Format Python code with psf/black push

* updating DIRECTORY.md

* updating DIRECTORY.md

* Fixed some suggested coding style issues

* Update rsa_key_generator.py

* Update rsa_key_generator.py
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: NJohn Law <johnlaw.po@gmail.com>

* Fix a failing precommit test

* updating DIRECTORY.md
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* graphs/kruskal: add doctest & type hints

this is a child of a previous PR #2443

its ancestor is #2128

* updating DIRECTORY.md

* graphs/kruskal: fix max-line-length violation

* fixup! Format Python code with psf/black push
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* Added solution for Project Euler problem 74. Fixes: #2695

* Added doctest for solution() in project_euler/problem_74/sol1.py

* Update docstrings and 0-padding of directory name. Reference: #3256

* Tighten up quicksort()

* updating DIRECTORY.md

* str does not support .pop()
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* add natural_sort.py

* fix doctest

* add 're' to requirements.txt and fix spelling errors

* delete 're' from requirements.txt

* fixing linting errors

* Update sorts/natural_sort.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update sorts/natural_sort.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update natural_sort.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Revert recent changes to .pre-commit-config.yaml

We must continue to insist that algorithmic functions can not print() as discussed in CONTRIBUTING.md.

* updating DIRECTORY.md
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* add binary_tree_traversals.py to data_structures

I have added some interesting binary tree traversing methods.

* Fixed error

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update binary_tree_traversals.py

* Update binary_tree_traversals.py

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update binary_tree_traversals.py

* Update data_structures/binary_tree/binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Update binary_tree_traversals.py

* Doctests and type hints

* Add spaces

* Update binary_tree_traversals.py

* black exclude data_structures/binary_tree/binary_tree_traversals.py

* Add spaces again

* Update binary_tree_traversals.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Added solution for Project Euler problemm problem 173. #2695

* Added docstring

* Update formatting, doctest and annotations. Reference: #3256

* Added solution for Project Euler problem 113. #2695

* Updated formatting and doctests. Reference: #3256

* .pre-commit-config.yaml: Disable trailing-whitespace fixer

* updating DIRECTORY.md
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* Update mergesort.py

1) Updating the merge sort in python as the previous implementation was modifying the input array
2) divided the division part and conquer part of the merge sort algorithm as 2 functions namely mergeSort and merge.
3) function mergeSort divides the function into halves i.e the purpose of the function will be to divide the array
4) function merge will merge 2 halves into a sorted array
5)Added random test cases using shuffle as suggested by @dhruvmanila
6 The time and space complexity of the previous and my version remains the same. i.e (n log(n) time and n log(n) space
7) changed variables as per the python case as required and suggested by @dhruvmanila
8) Updated function names as suggested by @dhurvmanila

* Update mergesort.py

Added in few more test cases 
added type hints for the functions and parameters as suggested by @dhruvmanila
formatted the code using Auto Pep8

* Update mergesort.py

update and added new testcases

* Update mergesort.py

Added in doc test in merge function

* Update mergesort.py

fixing pre-commit fails

* Update mergesort.py
Co-authored-by: NDhruv <dhruvmanila@gmail.com>

* Rename all Project Euler directories:

Reason:
The change was done to maintain consistency throughout the directory
and to keep all directories in sorted order.

Due to the above change, some config files had to be modified:
'problem_22` -> `problem_022`

* Update scripts to pad zeroes in PE directories

* Update README.md for Project Euler

* Add link to solution template

* Add newlines for better separation

* Add __name__ == __main__ block in template

* Apply suggestions from code review
Co-authored-by: NJohn Law <johnlaw.po@gmail.com>

* Improve introduction part
Co-authored-by: NJohn Law <johnlaw.po@gmail.com>

* Add solution for Project Euler 62

* Add doctests and annotate function params and return values for get_digits()

* Add extra newline between functions to fix flake8 errors

* Add extra newlines between function names

* Add missing return type for solution()

* Remove parenthesis from if statement

* Remove parentheses from while loop

* Add to explanation and fix second Travis build

* Compress get_digits(), add tests for solution(), add fstring and positional arg for solution()

* Remove input param when calling solution()

* Remove test case for the answer

* Removed an extra '=' which was creating an error while running a program.

* Removed the unexpected expression part.

* Added program for swap cases in string folder

* removed if condition and exchange word with char

* added '=' sign which I removed before because of unknowing error from pycharm

* added space in test

* removed costraint from problem statement

* Update cocktail_shaker_sort.py

* Update naive_string_search.py

* Update swap_case.py

* psf/black " not '

* added new line at the end of the file

* Fix flake8 issues

* added new line at the end of the file

* added True and fixed comment

* python file end with \n

* Update swap_case.py

* Update strings/swap_case.py

* Update strings/swap_case.py

* Apply suggestions from code review

* Update strings/swap_case.py

* Update swap_case.py

* Update swap_case.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* codespell.yml: Remove unused install of flake8

* updating DIRECTORY.md
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

* Add skew heap data structure.

* fixup! Add skew heap data structure.

* fixup! Add skew heap data structure.

* fixup! Add skew heap data structure.

* Add tests.

* Add __iter__ method.

* fixup! Add __iter__ method.

* Added decimal_to_binary_recursion.py

* Added decimal_to_binary_recursion.py

* Made changes to docstring

* Use divmod()

* binary_recursive(div) + str(mod)

* Be kind with user input if possible

* Update decimal_to_binary_recursion.py

* ValueError: invalid literal for int() with base 10: 'number'
Co-authored-by: NChristian Clauss <cclauss@me.com>

* added code to perform quantum entanglement

* Update quantum_entanglement.py

* Added binary tree mirror algorithm

* Minor changes

* Resolved comments

* Minor Changes

* resolved comments and updated doctests

* updated doctests

* updating DIRECTORY.md
Co-authored-by: Nsvedire <VedireSusmith_Reddy@intuit.com>
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>

this will fix code from randomly throwing `SystemExit: The affine cipher becomes weak when key B is set to 0. Choose different key` exception.

* Update CODEOWNERS

* Reduce @cclauss notifications during Hacktoberfest
Co-authored-by: NChristian Clauss <cclauss@me.com>