Fizz Buzz

EasyalgorithmsSimulation with modular arithmetic

Maintained by Vikas Dulgunde, software engineer

You are given a single positive integer n. Walk through the whole numbers from 1 up to and including n and decide what each one becomes in the output.

The rule depends on divisibility. A number divisible by 3 turns into "Fizz", a number divisible by 5 turns into "Buzz", and a number divisible by both 3 and 5 turns into "FizzBuzz". Any number that is divisible by neither stays as its own value, written as a string.

Return the results in order, so position i of the output corresponds to the number i (counting from 1). The output always has exactly n entries, and every entry is a string.

Examples

Input: n = 5

Output: ["1", "2", "Fizz", "4", "Buzz"]

1 and 2 are plain numbers, 3 is a multiple of 3 so it becomes Fizz, 4 is plain, and 5 is a multiple of 5 so it becomes Buzz.

Input: n = 15

Output: ["1", "2", "Fizz", "4", "Buzz", "Fizz", "7", "8", "Fizz", "Buzz", "11", "Fizz", "13", "14", "FizzBuzz"]

15 is the first number divisible by both 3 and 5, so it becomes FizzBuzz. Every third slot is Fizz and every fifth slot is Buzz, except where they overlap.

Input: n = 1

Output: ["1"]

1 is divisible by neither 3 nor 5, so it stays as the string "1".

Constraints

1 <= n <= 10^4
Every element of the returned list is a string, including the plain numbers.
The list is 1-indexed: position i holds the answer for the integer i.

Visible test cases

fizzBuzz(5) == ["1","2","Fizz","4","Buzz"]
fizzBuzz(15) == ["1","2","Fizz","4","Buzz","Fizz","7","8","Fizz","Buzz","11","Fizz","13","14","FizzBuzz"]

Hints

Hint 1

Loop from 1 to n and handle one number at a time. The hard part is only choosing which of the four outputs each number gets.

Hint 2

Order your checks carefully. Test divisibility by both 3 and 5 first, otherwise a multiple of 15 would match the Fizz branch and never reach FizzBuzz.

Hint 3

A number is divisible by both 3 and 5 exactly when it is divisible by 15, so a single i % 15 check captures the overlap.

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Approaches

Direct divisibility check

Time O(n) · Space O(1) extra, ignoring the O(n) output that must be returned

Iterate once through 1..n and pick the output for each value using modulo tests, checking the combined 3-and-5 case before the single cases.

Create an empty result list.
For each i from 1 to n, test i % 15 == 0 first and push "FizzBuzz" if true.
Otherwise test i % 3 == 0 for "Fizz", then i % 5 == 0 for "Buzz".
If none match, push the number converted to a string.
Return the result list after the loop.

String concatenation without explicit 15 check

Time O(n) · Space O(1) extra, ignoring the required O(n) output

Build each entry by appending "Fizz" when divisible by 3 and "Buzz" when divisible by 5, which produces "FizzBuzz" automatically for multiples of both and avoids a separate combined test.

For each i from 1 to n, start with an empty string s.
If i % 3 == 0, append "Fizz" to s.
If i % 5 == 0, append "Buzz" to s.
If s is still empty, set it to the string form of i.
Push s and return the list at the end.

Common mistakes

Checking i % 3 before the combined case, so multiples of 15 wrongly become "Fizz" instead of "FizzBuzz".
Returning numbers instead of strings; the plain values must be converted, so 4 becomes "4".
Off-by-one ranges: the list is 1-indexed and inclusive of n, so the loop must start at 1 and run through n, giving exactly n entries.
Using i % 3 == 0 || i % 5 == 0 as the FizzBuzz condition, which is too broad; the combined case needs both, that is i % 15 == 0.

Follow-up variations

Make the word rules configurable, for example a map of {3: "Fizz", 5: "Buzz", 7: "Bazz"} applied in ascending key order.
Stream or print the values for very large n without holding the whole list in memory.
Return the count of each category (how many Fizz, Buzz, FizzBuzz, and plain numbers) instead of the full list.

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Examples

Input: n = 5

Output: ["1", "2", "Fizz", "4", "Buzz"]

1 and 2 are plain numbers, 3 is a multiple of 3 so it becomes Fizz, 4 is plain, and 5 is a multiple of 5 so it becomes Buzz.

Input: n = 15

Output: ["1", "2", "Fizz", "4", "Buzz", "Fizz", "7", "8", "Fizz", "Buzz", "11", "Fizz", "13", "14", "FizzBuzz"]

15 is the first number divisible by both 3 and 5, so it becomes FizzBuzz. Every third slot is Fizz and every fifth slot is Buzz, except where they overlap.

Input: n = 1

Output: ["1"]

1 is divisible by neither 3 nor 5, so it stays as the string "1".

Hints

Hint 1

Loop from 1 to n and handle one number at a time. The hard part is only choosing which of the four outputs each number gets.

Hint 2

Order your checks carefully. Test divisibility by both 3 and 5 first, otherwise a multiple of 15 would match the Fizz branch and never reach FizzBuzz.

Hint 3

A number is divisible by both 3 and 5 exactly when it is divisible by 15, so a single i % 15 check captures the overlap.

Approaches

Direct divisibility check

Time O(n) · Space O(1) extra, ignoring the O(n) output that must be returned

Iterate once through 1..n and pick the output for each value using modulo tests, checking the combined 3-and-5 case before the single cases.

Create an empty result list.
For each i from 1 to n, test i % 15 == 0 first and push "FizzBuzz" if true.
Otherwise test i % 3 == 0 for "Fizz", then i % 5 == 0 for "Buzz".
If none match, push the number converted to a string.
Return the result list after the loop.

String concatenation without explicit 15 check

Time O(n) · Space O(1) extra, ignoring the required O(n) output

Build each entry by appending "Fizz" when divisible by 3 and "Buzz" when divisible by 5, which produces "FizzBuzz" automatically for multiples of both and avoids a separate combined test.

For each i from 1 to n, start with an empty string s.
If i % 3 == 0, append "Fizz" to s.
If i % 5 == 0, append "Buzz" to s.
If s is still empty, set it to the string form of i.
Push s and return the list at the end.

Common mistakes

Checking i % 3 before the combined case, so multiples of 15 wrongly become "Fizz" instead of "FizzBuzz".

Returning numbers instead of strings; the plain values must be converted, so 4 becomes "4".

Off-by-one ranges: the list is 1-indexed and inclusive of n, so the loop must start at 1 and run through n, giving exactly n entries.

Using i % 3 == 0 || i % 5 == 0 as the FizzBuzz condition, which is too broad; the combined case needs both, that is i % 15 == 0.

Follow-up variations

Make the word rules configurable, for example a map of {3: "Fizz", 5: "Buzz", 7: "Bazz"} applied in ascending key order.

Stream or print the values for very large n without holding the whole list in memory.

Return the count of each category (how many Fizz, Buzz, FizzBuzz, and plain numbers) instead of the full list.

Fizz Buzz

Examples

Constraints

Hints

Approaches

Direct divisibility check

String concatenation without explicit 15 check

Common mistakes

Follow-up variations

Recommended problems

Build the rest of your prep

Fizz Buzz

Examples

Constraints

Hints

Approaches

Direct divisibility check

String concatenation without explicit 15 check

Common mistakes

Follow-up variations

Recommended problems

Build the rest of your prep