[Project Euler] Algorithms do not follow coding styles

Many algorithms in Project Euler do not follow coding styles as mentioned by @dhruvmanila here, or even the standard coding guidelines.

Notes:

• A lot of inconsistencies with the solution functions (a lot of them aren't named as "solution")
• docstring inconsistencies:

>```docstring```
vs
>```
docstring```

• CONTRIBUTING.md says:

The following are considered to be bad and may be requested to be improved:
>>> x = x + 2	# increased by 2
This is too trivial. Comments are expected to be explanatory. For comments, you can write them above, on or below a line of code, as long as you are consistent within the same piece of code.

But there are places where this isn't practised.

Python/project_euler/problem_30/soln.py

Line 36 in b934da4

print(count) # --> 443839

• Python typehints don't seem to be present in the initial problem solutions.
  

  Python/project_euler/problem_01/sol1.py

  Line 9 in b934da4

  def solution(n):

  Python/project_euler/problem_01/sol2.py

  Line 9 in b934da4

  def solution(n):

• Filename inconsistencies. example

The list isn't complete.
As a beginner who's looking to either understand/contribute, this makes it a bit difficult.

[dhruvmanila]

UPDATE: As this is getting closer and closer to being fixed and the number of files per directory is reducing, you can create a PR fixing files in maximum 2 directories.

This is a completely valid issue. The thing is:

• Those initial solutions were submitted a long time ago
• I don't think consistency was maintained back then

Now as the number of solutions is increasing we need to enforce some of the consistency. One of the main ones was as I mentioned in #2695 (comment) but as you said there are many more. We can start with this and fix one issue at a time.

Due to some of the solutions not containing solution() function or requires some number of positional arguments we have decided to skip this script for now which checks for the solutions for every problem present. We can start fixing this first and then move on to other issues mentioned.

Submit the fix for one maximum two directories at a time and once that is approved, submit another one.

These are the errors which need to be fixed before we can start running the script in our tests:
https://travis-ci.com/github/TheAlgorithms/Python/jobs/394777235#L240-L312

These two are the main messages to look for in the above log:

1. solution() missing 1 required positional argument: 'n'
2. module 'sol1.py' has no attribute 'solution'

• The first one says that we have a solution() function but that requires a positional argument so to fix that put the default value for those parameters as the question input such that when we call the function without any arguments it returns the answer.
• The second one says that the specific file doesn't contain any solution() function so we need to either add the function or change the name of the present function, which returns the answer, to solution() and if it takes any positional arguments, to do the same thing as mentioned in the first point.

Current Status:

• problem_234/sol1.py: solution() missing 1 required positional argument: 'n'