Classic FizzBuzz: return a list from 1 to n with Fizz/Buzz substitutions.

Interview question: FizzBuzz

Given an integer `n`, return a list of strings from `1` to `n` where:

- multiples of 3 are replaced with `"Fizz"`,
- multiples of 5 with `"Buzz"`,
- multiples of both 3 and 5 with `"FizzBuzz"`,
- otherwise the number itself as a string.

- For every number from `1` through `n`, return one string.
- Multiples of `3` become `Fizz`, multiples of `5` become `Buzz`.
- Multiples of both must become `FizzBuzz`, not just one of the two words.

Understand the Replacement Rules

- A number divisible by both `3` and `5` is divisible by `15`.
- Check this case before checking only `3` or only `5`.
- Otherwise `15` would incorrectly be labeled as just `Fizz` or just `Buzz`.

Check the Most Specific Case First

- Use `range(1, n + 1)` because the sequence includes both endpoints: `1` and `n`.
- Append the correct string for each number.
- Convert normal numbers with `str(num)`.

Loop Through the Range

- The problem describes `n` as an integer, but JSON input can sometimes provide numeric-looking values as strings.
- Converting with `int(n)` makes the function tolerant of either form.
- The output remains a list of strings.

Handle Input Robustly

- The final solution makes one pass from `1` to `n` and applies the divisibility rules.
- Time complexity is O(n).
- Space complexity is O(n) for the returned list.