Solve the Easy-level FizzBuzz coding interview problem online in Python & JavaScript. Run your code against real test cases in the browser and study worked examples. It covers strings and math. Read the step-by-step solution and complexity analysis. Java starter code is also included for reference (no in-browser JVM yet, so it can't be run here).

FizzBuzz – Solve Online in Python & JavaScript

Contains Duplicate

Spiral Matrix

Produce the classic FizzBuzz sequence using divisibility rules.

Return strings for the integers from `1` through `n`. Use `"FizzBuzz"` for multiples of both 3 and 5, `"Fizz"` for multiples of 3, `"Buzz"` for multiples of 5, and the decimal number otherwise.

**Input / output**
- Input: `n: integer`
- Output: `string[]` of length `n`

**Examples**
1. `n = 5` returns `["1","2","Fizz","4","Buzz"]`.
2. At `n = 15`, the final value is `"FizzBuzz"`.

**Constraints**
- `1 <= n <= 10,000`

**Follow-up**
How would you make the rules data-driven so new divisors and labels can be added without another conditional branch?

- 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.