factorial

Your mission

Implement a function that returns the factorial of n, the product of every integer from 1 to n, with the factorial of 0 defined as 1.

See it in action

factorial(5)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Solve this with recursion: factorial(n) calls itself as n * factorial(n - 1).
The base case is factorial(0), which returns 1.
A negative n is an invalid input: return -1.
Assume n stays within the range where the result fits in an int (up to 12).

More examples

factorial(0)

Expected result

factorial(-3)

Expected result

-1

Constraints

Expected files

factorial.c

Allowed functions

None. Write every helper yourself.

factorial

Recursion

Your mission

Implement a function that returns the factorial of n, the product of every integer from 1 to n, with the factorial of 0 defined as 1.

See it in action

factorial(5)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Solve this with recursion: factorial(n) calls itself as n * factorial(n - 1).
The base case is factorial(0), which returns 1.
A negative n is an invalid input: return -1.
Assume n stays within the range where the result fits in an int (up to 12).

More examples

factorial(0)

Expected result

factorial(-3)

Expected result

-1

Constraints

Expected files

factorial.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Base case zeroWaiting

02Base case oneWaiting

03Small valueWaiting

04Typical valueWaiting

05Larger valueWaiting

06Largest value that fits in an intWaiting

07Negative input is invalidWaiting

factorial

Your mission

Implement a function that returns the factorial of n, the product of every integer from 1 to n, with the factorial of 0 defined as 1.

See it in action

factorial(5)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Solve this with recursion: factorial(n) calls itself as n * factorial(n - 1).
The base case is factorial(0), which returns 1.
A negative n is an invalid input: return -1.
Assume n stays within the range where the result fits in an int (up to 12).

More examples

factorial(0)

Expected result

factorial(-3)

Expected result

-1

Constraints

Expected files

factorial.c

Allowed functions

None. Write every helper yourself.

factorial

Recursion

Your mission

Implement a function that returns the factorial of n, the product of every integer from 1 to n, with the factorial of 0 defined as 1.

See it in action

factorial(5)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Solve this with recursion: factorial(n) calls itself as n * factorial(n - 1).
The base case is factorial(0), which returns 1.
A negative n is an invalid input: return -1.
Assume n stays within the range where the result fits in an int (up to 12).

More examples

factorial(0)

Expected result

factorial(-3)

Expected result

-1

Constraints

Expected files

factorial.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Base case zeroWaiting

02Base case oneWaiting

03Small valueWaiting

04Typical valueWaiting

05Larger valueWaiting

06Largest value that fits in an intWaiting

07Negative input is invalidWaiting