Knapsack

[Supriyasus]

Describe your change:

Added an enhanced implementation of the 0-N Knapsack Problem that includes both:

• A recursive version (optimized using functools.cache)
• A dynamic programming (DP) version for better performance on larger inputs

The code now adheres to PEP 8 and Ruff style rules, replacing @lru_cache(maxsize=None) with @cache (UP033) and ensuring all lines are ≤ 88 characters (E501).
Additionally, the function API has been simplified — the redundant counter parameter was removed, and a new method argument was added to choose between 'recursive' and 'dp' implementations.

Doctests and documentation have been updated to reflect these improvements.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

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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 description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".