README
cached-factorial
Utilize cached-expression to calculate multiple factorial numbers
Usage
import CachedFactorial from 'cached-factorial'
const { calculate } = new CachedFactorial()
const result = [0, 1, 2, 3, 4, 5].map(calculate) // expect: [1, 1, 2, 6, 24, 120]
Use Case: Factorials of Multiple Numbers
This is only useful when you have to calculate factorials of more than on number.
Why and How?
Let's say you have to calculate 5! and 7!. That gives us:
5! = 5 * 4 * 3 * 2 * 1
7! = 7 * 6 * (5 * 4 * 3 * 2 * 1) = 7 * 6 * 5!
If you were to calculate 5! and 7! independently, 5! (and by extension, 4!, 3!, 2!) will be called twice. This is wasteful!
In order to avoid this wasteful operation, CachedFactorial stores every factorial that is calculated in a cache so that every factorial is only computed once.