Create min_stack.py

[mavenzer]

Describe your change:

Creating a Min Stack that can give minimum element in stack in constant time.

• [ ✔] 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}.

[cclauss]

Why? There is no description when or why this algorithm would be useful. No doctests to prove that it works as intended. Python method names should be in snake_case as discussed in CONTRIBUTING.md. Seems like a lot of code for an algorithm that could be implemented in 5 lines of Python.

[Abdujabbar]

add some doctests

[mavenzer]

Updated min_stack.py with doc test and snake_case function definition.

[cclauss]

Please see #2477 (comment) and implement .__iter__() and .__len__() methods for this class. .__iter__() should return values in min-to-max order.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

Please reopen this pull request once you commit the changes requested or make improvements on the code. If this is not the case and you need some help, feel free to seek help from our Gitter or ping one of the reviewers. Thank you for your contributions!