Exercise: Iterative Factorial

Background/Motivation

The factorial of a non-negative integer $n$, denoted by $n!$, is the product of all positive integers less than or equal to $n$. Factorials are used in many areas of mathematics, including combinatorics, algebra, and mathematical analysis. Calculating a factorial is a classic example used to teach loop-based accumulation and is often compared with its recursive implementation.

The Task

Implement a function factorial_iterative(n: int) -> int that calculates the factorial of $n$ using a loop.

Specifications

Function Name: factorial_iterative
Arguments: n (int)
Return Type: int
Expected Output: The value of $n!$. For $n=0$, $0! = 1$.

Constraints

$0 \le n \le 50$

Example

>>> factorial_iterative(0)
1
>>> factorial_iterative(5)
120
>>> factorial_iterative(10)
3628800

Instructions

Open exercises/factorial_iterative/solution.py.
Implement the factorial_iterative function.
Change SUBMIT = False to SUBMIT = True at the top of the file when you are ready to be graded.
Run python solution.py locally to verify your solution with the built-in self-tests.