Factorial

Compute the factorial of a given input non-negative integer.

Exercise

Design and implement a method that computes factorial of the input non-negative integer and returns it.
Factorial of a number, 'n' is represented as n! and is defined as follows:
- 0! = 1
- n! = n * (n-1)! if n > 0
- ```
 = *n * (n-1) * (n-2) * ... * 1*
```
For example, 3! = 3 * 2 * 1 = 6. 6! = 720.
Share and explain the time and space complexities for your solution.
If you think of multiple approaches to solve the problem, implement the solution which minimizes space complexity. Explain the other approaches, and your decision in comments above the code.

Further reading: Learn more on Factorial to be prepared to answer similar questions to the one we did in this exercise.