In `@Mathematics/Fundamentals/HackerRank/Claude/Easy/Best`
Divisor/BestDivisor.ipynb around lines 2 - 6, The notebook currently has all
Python code inside Markdown, so add executable code cells containing the
implementation and tests: create a code cell that defines the Solution class
(e.g., class Solution with bestDivisor method) and another code cell with
runnable validation (simple asserts or a small unittest / if __name__ ==
"__main__": block that runs sample inputs and prints results) so readers can run
and verify behavior interactively; ensure any helper functions referenced by
Solution are also moved into code cells and that the test cells cover the
examples mentioned in the markdown.

In `@Mathematics/Fundamentals/HackerRank/Claude/Easy/Best`
Divisor/BestDivisor.ipynb around lines 69 - 70, Update the time-complexity notes
in the docstrings/comments for findBestDivisor and findBestDivisorCompetitive to
account for the per-divisor digit-sum cost: change the complexity from O(√n + d)
(and O(√n) for the competitive variant) to O(√n + d·log n) (or more precisely
O(√n + d * digits(n))) because _select_best_divisor iterates over d divisors and
computes digit sums in O(log n) each; update the two locations referenced
(around findBestDivisor and findBestDivisorCompetitive) accordingly.

In `@Mathematics/Fundamentals/HackerRank/Claude/Easy/Best`
Divisor/BestDivisor.ipynb around lines 102 - 108, The _validate_input method
lets bool pass because isinstance(True, int) is True; update _validate_input to
explicitly reject bools by either checking if type(n) is int (instead of
isinstance) or adding an early check like if isinstance(n, bool): raise
TypeError(...), then keep the existing range check and error messages unchanged
so True/False are not treated as integers.

In `@Mathematics/Fundamentals/HackerRank/Claude/Easy/Best`
Divisor/BestDivisor.ipynb around lines 199 - 205, Notebook shows two
inconsistent APIs: a Solution class method findBestDivisorCompetitive called as
solution.findBestDivisorCompetitive(n) in one cell and a standalone function
findBestDivisor(n) called as result = findBestDivisor(n) in another; pick one
pattern and unify all cells to it. If you choose the class approach, rename the
standalone function to a method on class Solution (e.g., implement
findBestDivisorCompetitive inside Solution), update all calls to use
solution.findBestDivisorCompetitive(n), and ensure the main block constructs
Solution() once; if you choose the standalone function, remove or refactor the
Solution class so the main block calls findBestDivisor(n) everywhere and update
explanatory text to match the chosen API. Ensure function/method names
(findBestDivisor, findBestDivisorCompetitive) and the main block calls are
consistent across all referenced cells (including lines 352-361).

In `@Mathematics/Fundamentals/HackerRank/Claude/Easy/Best`
Divisor/BestDivisor.ipynb around lines 386 - 393, The current divisor loop
iterates for d in (i, n // i) and thus processes the same divisor twice when i
== n // i (perfect square); update the logic in the while loop that uses i, n,
best_sum, best and d to avoid duplicate work by handling the square-case: either
branch so that when i == n // i you compute the digit sum and comparison once,
otherwise process both i and n // i (or add a guard inside the for-loop to skip
when d == n // i and i == n // i); ensure the comparisons still use best and
best_sum.